Learning Outcomes
- Define atomic and mass numbers.
- Determine the number of protons, neutrons, and electrons in an atom.
- Identify the charge and relative mass of subatomic particles.
- Label the location of subatomic particles in the atom.
- Define isotope.
- Write the isotopic symbol of an atom.
- Explain the concept of average atomic mass.
Quarry 1.0 Replace Stuff ResearchPal KV RimFridge - 1.0 While You're Up 1.0 RT Fuse RT Power Switch RT Solar Flare Shield KV Save Storage, Outfit, Crafting, Drug, & Operation Settings - 1.0. Define 'isotope' using mass number, atomic number, number of protons, neutrons and electrons. Given information about an element, find the mass and name of an isotope. Give evidence to support or dispute: 'In nature, the chance of finding one isotope of an element is the same for all isotopes.'. .43.2 kg (1 s/0.0135 kg) (1 hr/ 3600 s) = 0889 hr A pycnometer is a glass flask with a tight fitting glass stopper that is used to obtain the volume of a liquid with high accuracy. A pycnometer has a mass of 25.151 grams when empty, and a mass of 42.481 grams when completely filled with water.
Atoms are the fundamental building blocks of all matter and are composed of protons, neutrons, and electrons. Because atoms are electrically neutral, the number of positively charged protons must be equal to the number of negatively charged electrons. Since neutrons do not affect the charge, the number of neutrons is not dependent on the number of protons and will vary even among atoms of the same element.
Atomic Number
Atomic 1 0 42 Percent
The atomic number (Z)of an element is the number of protons in the nucleus of each atom of that element. An atom can be classified as a particular element based solely on its atomic number. For example, any atom with an atomic number of 8 (its nucleus contains 8 protons) is an oxygen atom, and any atom with a different number of protons would be a different element. The periodic table (see figure below) displays all of the known elements and is arranged in order of increasing atomic number. In this table, an element's atomic number is indicated above the elemental symbol. Hydrogen, at the upper left of the table, has an atomic number of 1. Every hydrogen atom has one proton in its nucleus. Next on the table is helium, whose atoms have two protons in the nucleus. Lithium atoms have three protons, beryllium atoms have four, and so on.
Since atoms are neutral, the number of electrons in an atom is equal to the number of protons. Hydrogen atoms all have one electron occupying the space outside of the nucleus. Helium, with two protons, will have two electrons.
Mass Number
Experimental data showed that the vast majority of the mass of an atom is concentrated in its nucleus, which is composed of protons and neutrons. The mass numberis defined as the total number of protons and neutrons in an atom. Consider the table below, which shows data from the first six elements of the periodic table.
| Name | Symbol | Atomic Number | Protons | Neutrons | Electrons | Mass Number |
|---|---|---|---|---|---|---|
| hydrogen | (ce{H}) | 1 | 1 | 0 | 1 | 1 |
| helium | (ce{He}) | 2 | 2 | 2 | 2 | 4 |
| lithium | (ce{Li}) | 3 | 3 | 4 | 3 | 7 |
| beryllium | (ce{Be}) | 4 | 4 | 5 | 4 | 9 |
| boron | (ce{B}) | 5 | 5 | 6 | 5 | 11 |
| carbon | (ce{C}) | 6 | 6 | 6 | 6 | 12 |
View animations showing the atomic structure of the first 11 elements on the periodic table at http://web.visionlearning.com/custom..imations.shtml
Consider the element helium. Its atomic number is 2, so it has two protons in its nucleus. Its nucleus also contains two neutrons. Since (2 + 2 = 4), we know that the mass number of the helium atom is 4. Finally, the helium atom also contains two electrons, since the number of electrons must equal the number of protons. This example may lead you to believe that atoms have the same number of protons and neutrons, but a further examination of the table above will show that this is not the case. Lithium, for example, has three protons and four neutrons, giving it a mass number of 7.
Knowing the mass number and the atomic number of an atom allows you to determine the number of neutrons present in that atom by subtraction.
[text{Number of neutrons} = text{mass number} - text{atomic number}]
Atoms of the element chromium (left( ce{Cr} right)) have an atomic number of 24 and a mass number of 52. How many neutrons are in the nucleus of a chromium atom? To determine this, you would subtract as shown:
[52 - 24 = 28 : text{neutrons in a chromium atom}]
Atomic 1/28
The composition of any atom can be illustrated with a shorthand notation using the atomic number and the mass number. Both are written before the chemical symbol, with the mass number written as a superscript and the atomic number written as a subscript. The chromium atom discussed above would be written as:
[ce{^{52}_{24}Cr}]
Another way to refer to a specific atom is to write the mass number of the atom after the name, separated by a hyphen. The above atom would be written as chromium-52, with the mass number written after the name. The atomic number does not have to be included because all atoms of chromium have the same number of protons but can vary in the atomic mass.
Atomic 1 0 42 Inch
Isotopes
As stated earlier, not all atoms of a given element are identical. Specifically, the number of neutrons in the nucleus can vary for many elements. As an example, naturally occurring carbon exists in three forms, which are illustrated in the figure below.
Each carbon atom has the same number of protons (6), which is equal to its atomic number. Each carbon atom also contains six electrons, allowing the atom to remain electrically neutral. However, the number of neutrons varies from six to eight. Isotopesare atoms that have the same atomic number but different mass numbers due to a change in the number of neutrons. The three isotopes of carbon can be referred to as carbon-12 (left( ce{^{12}_6C} right)), carbon-13 (left( ce{^{13}_6C} right)), and carbon-14 (left( ce{^{14}_6C} right)). Naturally occurring samples of most elements are mixtures of isotopes. Carbon has only three natural isotopes, but some heavier elements have many more. Tin has ten stable isotopes, which is the most of any known element. The nucleus of a given carbon atom will be one of the three possible isotopes discussed above.
While the presence of isotopes affects the mass of an atom, it does not affect its chemical reactivity. Chemical behavior is governed by the number of electrons and the number of protons. Carbon-13 behaves chemically in exactly the same way as the more plentiful carbon-12.
Size of Atoms
The graphite in your pencil is composed of the element carbon, a nonmetal. Imagine taking a small piece of carbon and grinding it until it is a fine dust. Each speck of carbon would still have all of the physical and chemical properties of carbon. Now imagine that you could somehow keep dividing the speck of carbon into smaller and smaller pieces. Eventually, you would reach a point where your carbon sample is as small as it could possibly be. This final particle is called an atom.
Atoms, as you probably know, are extremely small. In fact, the graphite in an ordinary pencil contains about (5 times 10^{20}) atoms of carbon. This is an almost incomprehensibly large number. The population of the entire Earth is about (7 times 10^9) people, meaning that there are about (7 times 10^{10}) times as many carbon atoms in your pencil as there are people on Earth! For this to be true, atoms must be extremely small. We can only see atoms with a modern instrument called a scanning tunneling microscope. (www.nobelprize.org/educationa..opes/scanning/)
Atomic Mass
The masses of individual atoms are very, very small. However, using a modern device called a mass spectrometer, it is possible to measure such miniscule masses. An atom of oxygen-16, for example, has a mass of (2.66 times 10^{-23} : text{g}). While comparisons of masses measured in grams would have some usefulness, it is far more practical to have a system that will allow us to more easily compare relative atomic masses. Scientists decided on using the carbon-12 nuclide as the reference standard by which all other masses would be compared. By definition, one atom of carbon-12 is assigned a mass of exactly 12 atomic mass units (left( text{amu} right)). An atomic mass unitis defined as a mass equal to one twelfth of an atom of carbon-12. The mass of any isotope of any element is expressed in relation to the carbon-12 standard. For example, one atom of helium-4 has a mass of (4.0026 : text{amu}). An atom of sulfur-32 has a mass of (31.972 : text{amu}).
The carbon-12 atom has six protons and six neutrons in its nucleus for a mass number of 12. Since the nucleus accounts for nearly all of the mass of the atom, a single proton or single neutron has a mass of approximately (1 : text{amu}). However, as seen by the helium and sulfur examples, the masses of individual atoms are not quite whole numbers. This is because an atom's mass is affected very slightly by the interactions of the various particles within the nucleus and also includes the small mass added by each electron.
As stated in the section on isotopes, most elements occur naturally as a mixture of two or more isotopes. Listed below (see table below) are the naturally occurring isotopes of several elements along with the percent natural abundance of each.
| Element | Isotope (Symbol) | Percent Natural Abundance | Atomic mass (left( text{amu} right)) | Average atomic mass (left( text{amu} right)) |
|---|---|---|---|---|
| Hydrogen | (ce{^1_1H}) | 99.985 | 1.0078 | 1.0079 |
| (ce{^2_1H}) | 0.015 | 2.0141 | ||
| (ce{^3_1H}) | negligible | 3.0160 | ||
| Carbon | (ce{^{12}_6C}) | 98.89 | 12.000 | 12.011 |
| (ce{^{13}_6C}) | 1.11 | 13.003 | ||
| (ce{^{14}_6C}) | trace | 14.003 | ||
| Oxygen | (ce{^{16}_8O}) | 99.759 | 15.995 | 15.999 |
| (ce{^{17}_8O}) | 0.037 | 16.995 | ||
| (ce{^{18}_8O}) | 0.204 | 17.999 | ||
| Chlorine | (ce{^{35}_{17}Cl}) | 75.77 | 34.969 | 35.453 |
| (ce{^{37}_{17}Cl}) | 24.23 | 36.966 | ||
| Copper | (ce{^{63}_{29}Cu}) | 69.17 | 62.930 | 63.546 |
| (ce{^{65}_{29}Cu}) | 30.83 | 64.928 |
For some elements, one particular isotope is much more abundant than any other isotopes. For example, naturally occurring hydrogen is nearly all hydrogen-1, and naturally occurring oxygen is nearly all oxygen-16. For many other elements, however, more than one isotope may exist in substantial quantities. Chlorine (atomic number 17) is yellowish-green toxic gas. About three quarters of all chlorine atoms have 18 neutrons, giving those atoms a mass number of 35. About one quarter of all chlorine atoms have 20 neutrons, giving those atoms a mass number of 37. Were you to simply calculate the arithmetic average of the precise atomic masses, you would get approximately 36.
[frac{34.969 + 36.966}{2} = 35.968]
As you can see, the average atomic mass given in the last column of the table above is significantly lower. Why? The reason is that we need to take into account the natural abundance percentages of each isotope in order to calculate what is called the weighted average. The atomic massof an element is the weighted average of the atomic masses of the naturally occurring isotopes of that element. The average atomic masses are the values we see on the periodic table.
[0.7577 left( 34.969 right) + 0.2423 left( 36.966 right) = 35.453]
The weighted average is determined by multiplying the percent of natural abundance by the actual mass of the isotope. This is repeated until there is a term for each isotope. For chlorine, there are only two naturally occurring isotopes so there are only two terms.
Supplemental Resources
Isotopes
As stated earlier, not all atoms of a given element are identical. Specifically, the number of neutrons in the nucleus can vary for many elements. As an example, naturally occurring carbon exists in three forms, which are illustrated in the figure below.
Each carbon atom has the same number of protons (6), which is equal to its atomic number. Each carbon atom also contains six electrons, allowing the atom to remain electrically neutral. However, the number of neutrons varies from six to eight. Isotopesare atoms that have the same atomic number but different mass numbers due to a change in the number of neutrons. The three isotopes of carbon can be referred to as carbon-12 (left( ce{^{12}_6C} right)), carbon-13 (left( ce{^{13}_6C} right)), and carbon-14 (left( ce{^{14}_6C} right)). Naturally occurring samples of most elements are mixtures of isotopes. Carbon has only three natural isotopes, but some heavier elements have many more. Tin has ten stable isotopes, which is the most of any known element. The nucleus of a given carbon atom will be one of the three possible isotopes discussed above.
While the presence of isotopes affects the mass of an atom, it does not affect its chemical reactivity. Chemical behavior is governed by the number of electrons and the number of protons. Carbon-13 behaves chemically in exactly the same way as the more plentiful carbon-12.
Size of Atoms
The graphite in your pencil is composed of the element carbon, a nonmetal. Imagine taking a small piece of carbon and grinding it until it is a fine dust. Each speck of carbon would still have all of the physical and chemical properties of carbon. Now imagine that you could somehow keep dividing the speck of carbon into smaller and smaller pieces. Eventually, you would reach a point where your carbon sample is as small as it could possibly be. This final particle is called an atom.
Atoms, as you probably know, are extremely small. In fact, the graphite in an ordinary pencil contains about (5 times 10^{20}) atoms of carbon. This is an almost incomprehensibly large number. The population of the entire Earth is about (7 times 10^9) people, meaning that there are about (7 times 10^{10}) times as many carbon atoms in your pencil as there are people on Earth! For this to be true, atoms must be extremely small. We can only see atoms with a modern instrument called a scanning tunneling microscope. (www.nobelprize.org/educationa..opes/scanning/)
Atomic Mass
The masses of individual atoms are very, very small. However, using a modern device called a mass spectrometer, it is possible to measure such miniscule masses. An atom of oxygen-16, for example, has a mass of (2.66 times 10^{-23} : text{g}). While comparisons of masses measured in grams would have some usefulness, it is far more practical to have a system that will allow us to more easily compare relative atomic masses. Scientists decided on using the carbon-12 nuclide as the reference standard by which all other masses would be compared. By definition, one atom of carbon-12 is assigned a mass of exactly 12 atomic mass units (left( text{amu} right)). An atomic mass unitis defined as a mass equal to one twelfth of an atom of carbon-12. The mass of any isotope of any element is expressed in relation to the carbon-12 standard. For example, one atom of helium-4 has a mass of (4.0026 : text{amu}). An atom of sulfur-32 has a mass of (31.972 : text{amu}).
The carbon-12 atom has six protons and six neutrons in its nucleus for a mass number of 12. Since the nucleus accounts for nearly all of the mass of the atom, a single proton or single neutron has a mass of approximately (1 : text{amu}). However, as seen by the helium and sulfur examples, the masses of individual atoms are not quite whole numbers. This is because an atom's mass is affected very slightly by the interactions of the various particles within the nucleus and also includes the small mass added by each electron.
As stated in the section on isotopes, most elements occur naturally as a mixture of two or more isotopes. Listed below (see table below) are the naturally occurring isotopes of several elements along with the percent natural abundance of each.
| Element | Isotope (Symbol) | Percent Natural Abundance | Atomic mass (left( text{amu} right)) | Average atomic mass (left( text{amu} right)) |
|---|---|---|---|---|
| Hydrogen | (ce{^1_1H}) | 99.985 | 1.0078 | 1.0079 |
| (ce{^2_1H}) | 0.015 | 2.0141 | ||
| (ce{^3_1H}) | negligible | 3.0160 | ||
| Carbon | (ce{^{12}_6C}) | 98.89 | 12.000 | 12.011 |
| (ce{^{13}_6C}) | 1.11 | 13.003 | ||
| (ce{^{14}_6C}) | trace | 14.003 | ||
| Oxygen | (ce{^{16}_8O}) | 99.759 | 15.995 | 15.999 |
| (ce{^{17}_8O}) | 0.037 | 16.995 | ||
| (ce{^{18}_8O}) | 0.204 | 17.999 | ||
| Chlorine | (ce{^{35}_{17}Cl}) | 75.77 | 34.969 | 35.453 |
| (ce{^{37}_{17}Cl}) | 24.23 | 36.966 | ||
| Copper | (ce{^{63}_{29}Cu}) | 69.17 | 62.930 | 63.546 |
| (ce{^{65}_{29}Cu}) | 30.83 | 64.928 |
For some elements, one particular isotope is much more abundant than any other isotopes. For example, naturally occurring hydrogen is nearly all hydrogen-1, and naturally occurring oxygen is nearly all oxygen-16. For many other elements, however, more than one isotope may exist in substantial quantities. Chlorine (atomic number 17) is yellowish-green toxic gas. About three quarters of all chlorine atoms have 18 neutrons, giving those atoms a mass number of 35. About one quarter of all chlorine atoms have 20 neutrons, giving those atoms a mass number of 37. Were you to simply calculate the arithmetic average of the precise atomic masses, you would get approximately 36.
[frac{34.969 + 36.966}{2} = 35.968]
As you can see, the average atomic mass given in the last column of the table above is significantly lower. Why? The reason is that we need to take into account the natural abundance percentages of each isotope in order to calculate what is called the weighted average. The atomic massof an element is the weighted average of the atomic masses of the naturally occurring isotopes of that element. The average atomic masses are the values we see on the periodic table.
[0.7577 left( 34.969 right) + 0.2423 left( 36.966 right) = 35.453]
The weighted average is determined by multiplying the percent of natural abundance by the actual mass of the isotope. This is repeated until there is a term for each isotope. For chlorine, there are only two naturally occurring isotopes so there are only two terms.
Supplemental Resources
- Elements and Atoms: http://www.youtube.com/watch?v=IFKnq9QM6_A
- Introduction to the Atom: http://www.youtube.com/watch?v=1xSQIwWGT8M
- Atomic History - A Brief Discovery: http://www.pbs.org/wgbh/nova/diamond..dehistory.html
- All About Atoms: http://education.jlab.org/atomtour/index.html
- Build and Atom: http://phet.colorado.edu/en/simulation/build-an-atom
- Molecular Workbench - Atomic Structure: http://workbench.concord.org/databas..vities/47.html
- See Inside a Diamond: http://www.pbs.org/wgbh/nova/diamond/insidewave.html
- Isotopes and Atomic Mass: http://phet.colorado.edu/en/simulati..nd-atomic-mass
- Atomic Structure: freezeray.com/flashFiles/atomcStructure.htm
- Atom Builder: freezeray.com/flashFiles/atomBuilder.htm
- Tennis Ball Isotopes: http://www.youtube.com/watch?v=oLnuXpf4hsA
- Element Math Game: http://education.jlab.org/elementmath/index.html
- Atoms and Matter Crossword Puzzle: http://education.jlab.org/sciencecro../atoms_01.html
- Atomic Number Review #1: www.sciencegeek.net/Chemistry..micNumbers.htm
- Atomic Number Review #2: www.sciencegeek.net/Chemistry..t1Numbers2.htm
- Atomic Structure: www.sciencegeek.net/Chemistry..omicStructure/
Atomic 104 Clue Crossword
Contributors and Attributions
CK-12 Foundation by Sharon Bewick, Richard Parsons, Therese Forsythe, Shonna Robinson, and Jean Dupon.
Allison Soult, Ph.D. (Department of Chemistry, University of Kentucky)
Click a column title, such as Name, to sort the table by that item.
SEENotes at the bottom of the Table.
| No. | Atomic Weight | Name | Sym. | M.P. (°C) | B.P. (°C) | Density* (g/cm3) | Earth crust (%)* | Discovery (Year) | Group* | Electron configuration | Ionization energy (eV) | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 1.008 | Hydrogen | H | -259 | -253 | 0.09 | 0.14 | 1776 | 1 | 1s1 | 13.60 | |
| 2 | 4.003 | Helium | He | -272 | -269 | 0.18 | 1895 | 18 | 1s2 | 24.59 | ||
| 3 | 6.941 | Lithium | Li | 180 | 1,347 | 0.53 | 1817 | 1 | [He] 2s1 | 5.39 | ||
| 4 | 9.012 | Beryllium | Be | 1,278 | 2,970 | 1.85 | 1797 | 2 | [He] 2s2 | 9.32 | ||
| 5 | 10.811 | Boron | B | 2,300 | 2,550 | 2.34 | 1808 | 13 | [He] 2s2 2p1 | 8.30 | ||
| 6 | 12.011 | Carbon | C | 3,500 | 4,827 | 2.26 | 0.09 | ancient | 14 | [He] 2s2 2p2 | 11.26 | |
| 7 | 14.007 | Nitrogen | N | -210 | -196 | 1.25 | 1772 | 15 | [He] 2s2 2p3 | 14.53 | ||
| 8 | 15.999 | Oxygen | O | -218 | -183 | 1.43 | 46.71 | 1774 | 16 | [He] 2s2 2p4 | 13.62 | |
| 9 | 18.998 | Fluorine | F | -220 | -188 | 1.70 | 0.03 | 1886 | 17 | [He] 2s2 2p5 | 17.42 | |
| 10 | 20.180 | Neon | Ne | -249 | -246 | 0.90 | 1898 | 18 | [He] 2s2 2p6 | 21.56 | ||
| 11 | 22.990 | Sodium | Na | 98 | 883 | 0.97 | 2.75 | 1807 | 1 | [Ne] 3s1 | 5.14 | |
| 12 | 24.305 | Magnesium | Mg | 639 | 1,090 | 1.74 | 2.08 | 1755 | 2 | [Ne] 3s2 | 7.65 | |
| 13 | 26.982 | Aluminum | Al | 660 | 2,467 | 2.70 | 8.07 | 1825 | 13 | [Ne] 3s2 3p1 | 5.99 | |
| 14 | 28.086 | Silicon | Si | 1,410 | 2,355 | 2.33 | 27.69 | 1824 | 14 | [Ne] 3s2 3p2 | 8.15 | |
| 15 | 30.974 | Phosphorus | P | 44 | 280 | 1.82 | 0.13 | 1669 | 15 | [Ne] 3s2 3p3 | 10.49 | |
| 16 | 32.065 | Sulfur | S | 113 | 445 | 2.07 | 0.05 | ancient | 16 | [Ne] 3s2 3p4 | 10.36 | |
| 17 | 35.453 | Chlorine | Cl | -101 | -35 | 3.21 | 0.05 | 1774 | 17 | [Ne] 3s2 3p5 | 12.97 | |
| 18 | 39.948 | Argon | Ar | -189 | -186 | 1.78 | 1894 | 18 | [Ne] 3s2 3p6 | 15.76 | ||
| 19 | 39.098 | Potassium | K | 64 | 774 | 0.86 | 2.58 | 1807 | 1 | [Ar] 4s1 | 4.34 | |
| 20 | 40.078 | Calcium | Ca | 839 | 1,484 | 1.55 | 3.65 | 1808 | 2 | [Ar] 4s2 | 6.11 | |
| 21 | 44.956 | Scandium | Sc | 1,539 | 2,832 | 2.99 | 1879 | 3 | [Ar] 3d1 4s2 | 6.56 | ||
| 22 | 47.867 | Titanium | Ti | 1,660 | 3,287 | 4.54 | 0.62 | 1791 | 4 | [Ar] 3d2 4s2 | 6.83 | |
| 23 | 50.942 | Vanadium | V | 1,890 | 3,380 | 6.11 | 1830 | 5 | [Ar] 3d3 4s2 | 6.75 | ||
| 24 | 51.996 | Chromium | Cr | 1,857 | 2,672 | 7.19 | 0.04 | 1797 | 6 | [Ar] 3d5 4s1 | 6.77 | |
| 25 | 54.938 | Manganese | Mn | 1,245 | 1,962 | 7.43 | 0.09 | 1774 | 7 | [Ar] 3d5 4s2 | 7.43 | |
| 26 | 55.845 | Iron | Fe | 1,535 | 2,750 | 7.87 | 5.05 | ancient | 8 | [Ar] 3d6 4s2 | 7.90 | |
| 27 | 58.933 | Cobalt | Co | 1,495 | 2,870 | 8.90 | 1735 | 9 | [Ar] 3d7 4s2 | 7.88 | ||
| 28 | 58.693 | Nickel | Ni | 1,453 | 2,732 | 8.90 | 0.02 | 1751 | 10 | [Ar] 3d8 4s2 | 7.64 | |
| 29 | 63.546 | Copper | Cu | 1,083 | 2,567 | 8.96 | ancient | 11 | [Ar] 3d10 4s1 | 7.73 | ||
| 30 | 65.390 | Zinc | Zn | 420 | 907 | 7.13 | ancient | 12 | [Ar] 3d10 4s2 | 9.39 | ||
| 31 | 69.723 | Gallium | Ga | 30 | 2,403 | 5.91 | 1875 | 13 | [Ar] 3d10 4s2 4p1 | 6.00 | ||
| 32 | 72.640 | Germanium | Ge | 937 | 2,830 | 5.32 | 1886 | 14 | [Ar] 3d10 4s2 4p2 | 7.90 | ||
| 33 | 74.922 | Arsenic | As | 81 | 613 | 5.72 | ancient | 15 | [Ar] 3d10 4s2 4p3 | 9.79 | ||
| 34 | 78.960 | Selenium | Se | 217 | 685 | 4.79 | 1817 | 16 | [Ar] 3d10 4s2 4p4 | 9.75 | ||
| 35 | 79.904 | Bromine | Br | -7 | 59 | 3.12 | 1826 | 17 | [Ar] 3d10 4s2 4p5 | 11.81 | ||
| 36 | 83.800 | Krypton | Kr | -157 | -153 | 3.75 | 1898 | 18 | [Ar] 3d10 4s2 4p6 | 14.00 | ||
| 37 | 85.468 | Rubidium | Rb | 39 | 688 | 1.63 | 1861 | 1 | [Kr] 5s1 | 4.18 | ||
| 38 | 87.620 | Strontium | Sr | 769 | 1,384 | 2.54 | 1790 | 2 | [Kr] 5s2 | 5.69 | ||
| 39 | 88.906 | Yttrium | Y | 1,523 | 3,337 | 4.47 | 1794 | 3 | [Kr] 4d1 5s2 | 6.22 | ||
| 40 | 91.224 | Zirconium | Zr | 1,852 | 4,377 | 6.51 | 0.03 | 1789 | 4 | [Kr] 4d2 5s2 | 6.63 | |
| 41 | 92.906 | Niobium | Nb | 2,468 | 4,927 | 8.57 | 1801 | 5 | [Kr] 4d4 5s1 | 6.76 | ||
| 42 | 95.940 | Molybdenum | Mo | 2,617 | 4,612 | 10.22 | 1781 | 6 | [Kr] 4d5 5s1 | 7.09 | ||
| 43 | * | 98.000 | Technetium | Tc | 2,200 | 4,877 | 11.50 | 1937 | 7 | [Kr] 4d5 5s2 | 7.28 | |
| 44 | 101.070 | Ruthenium | Ru | 2,250 | 3,900 | 12.37 | 1844 | 8 | [Kr] 4d7 5s1 | 7.36 | ||
| 45 | 102.906 | Rhodium | Rh | 1,966 | 3,727 | 12.41 | 1803 | 9 | [Kr] 4d8 5s1 | 7.46 | ||
| 46 | 106.420 | Palladium | Pd | 1,552 | 2,927 | 12.02 | 1803 | 10 | [Kr] 4d10 | 8.34 | ||
| 47 | 107.868 | Silver | Ag | 962 | 2,212 | 10.50 | ancient | 11 | [Kr] 4d10 5s1 | 7.58 | ||
| 48 | 112.411 | Cadmium | Cd | 321 | 765 | 8.65 | 1817 | 12 | [Kr] 4d10 5s2 | 8.99 | ||
| 49 | 114.818 | Indium | In | 157 | 2,000 | 7.31 | 1863 | 13 | [Kr] 4d10 5s2 5p1 | 5.79 | ||
| 50 | 118.710 | Tin | Sn | 232 | 2,270 | 7.31 | ancient | 14 | [Kr] 4d10 5s2 5p2 | 7.34 | ||
| 51 | 121.760 | Antimony | Sb | 630 | 1,750 | 6.68 | ancient | 15 | [Kr] 4d10 5s2 5p3 | 8.61 | ||
| 52 | 127.600 | Tellurium | Te | 449 | 990 | 6.24 | 1783 | 16 | [Kr] 4d10 5s2 5p4 | 9.01 | ||
| 53 | 126.905 | Iodine | I | 114 | 184 | 4.93 | 1811 | 17 | [Kr] 4d10 5s2 5p5 | 10.45 | ||
| 54 | 131.293 | Xenon | Xe | -112 | -108 | 5.90 | 1898 | 18 | [Kr] 4d10 5s2 5p6 | 12.13 | ||
| 55 | 132.906 | Cesium | Cs | 29 | 678 | 1.87 | 1860 | 1 | [Xe] 6s1 | 3.89 | ||
| 56 | 137.327 | Barium | Ba | 725 | 1,140 | 3.59 | 0.05 | 1808 | 2 | [Xe] 6s2 | 5.21 | |
| 57 | 138.906 | Lanthanum | La | 920 | 3,469 | 6.15 | 1839 | 3 | [Xe] 5d1 6s2 | 5.58 | ||
| 58 | 140.116 | Cerium | Ce | 795 | 3,257 | 6.77 | 1803 | 101 | [Xe] 4f1 5d1 6s2 | 5.54 | ||
| 59 | 140.908 | Praseodymium | Pr | 935 | 3,127 | 6.77 | 1885 | 101 | [Xe] 4f3 6s2 | 5.47 | ||
| 60 | 144.240 | Neodymium | Nd | 1,010 | 3,127 | 7.01 | 1885 | 101 | [Xe] 4f4 6s2 | 5.53 | ||
| 61 | * | 145.000 | Promethium | Pm | 1,100 | 3,000 | 7.30 | 1945 | 101 | [Xe] 4f5 6s2 | 5.58 | |
| 62 | 150.360 | Samarium | Sm | 1,072 | 1,900 | 7.52 | 1879 | 101 | [Xe] 4f6 6s2 | 5.64 | ||
| 63 | 151.964 | Europium | Eu | 822 | 1,597 | 5.24 | 1901 | 101 | [Xe] 4f7 6s2 | 5.67 | ||
| 64 | 157.250 | Gadolinium | Gd | 1,311 | 3,233 | 7.90 | 1880 | 101 | [Xe] 4f7 5d1 6s2 | 6.15 | ||
| 65 | 158.925 | Terbium | Tb | 1,360 | 3,041 | 8.23 | 1843 | 101 | [Xe] 4f9 6s2 | 5.86 | ||
| 66 | 162.500 | Dysprosium | Dy | 1,412 | 2,562 | 8.55 | 1886 | 101 | [Xe] 4f10 6s2 | 5.94 | ||
| 67 | 164.930 | Holmium | Ho | 1,470 | 2,720 | 8.80 | 1867 | 101 | [Xe] 4f11 6s2 | 6.02 | ||
| 68 | 167.259 | Erbium | Er | 1,522 | 2,510 | 9.07 | 1842 | 101 | [Xe] 4f12 6s2 | 6.11 | ||
| 69 | 168.934 | Thulium | Tm | 1,545 | 1,727 | 9.32 | 1879 | 101 | [Xe] 4f13 6s2 | 6.18 | ||
| 70 | 173.040 | Ytterbium | Yb | 824 | 1,466 | 6.90 | 1878 | 101 | [Xe] 4f14 6s2 | 6.25 | ||
| 71 | 174.967 | Lutetium | Lu | 1,656 | 3,315 | 9.84 | 1907 | 101 | [Xe] 4f14 5d1 6s2 | 5.43 | ||
| 72 | 178.490 | Hafnium | Hf | 2,150 | 5,400 | 13.31 | 1923 | 4 | [Xe] 4f14 5d2 6s2 | 6.83 | ||
| 73 | 180.948 | Tantalum | Ta | 2,996 | 5,425 | 16.65 | 1802 | 5 | [Xe] 4f14 5d3 6s2 | 7.55 | ||
| 74 | 183.840 | Tungsten | W | 3,410 | 5,660 | 19.35 | 1783 | 6 | [Xe] 4f14 5d4 6s2 | 7.86 | ||
| 75 | 186.207 | Rhenium | Re | 3,180 | 5,627 | 21.04 | 1925 | 7 | [Xe] 4f14 5d5 6s2 | 7.83 | ||
| 76 | 190.230 | Osmium | Os | 3,045 | 5,027 | 22.60 | 1803 | 8 | [Xe] 4f14 5d6 6s2 | 8.44 | ||
| 77 | 192.217 | Iridium | Ir | 2,410 | 4,527 | 22.40 | 1803 | 9 | [Xe] 4f14 5d7 6s2 | 8.97 | ||
| 78 | 195.078 | Platinum | Pt | 1,772 | 3,827 | 21.45 | 1735 | 10 | [Xe] 4f14 5d9 6s1 | 8.96 | ||
| 79 | 196.967 | Gold | Au | 1,064 | 2,807 | 19.32 | ancient | 11 | [Xe] 4f14 5d10 6s1 | 9.23 | ||
| 80 | 200.590 | Mercury | Hg | -39 | 357 | 13.55 | ancient | 12 | [Xe] 4f14 5d10 6s2 | 10.44 | ||
| 81 | 204.383 | Thallium | Tl | 303 | 1,457 | 11.85 | 1861 | 13 | [Xe] 4f14 5d10 6s2 6p1 | 6.11 | ||
| 82 | 207.200 | Lead | Pb | 327 | 1,740 | 11.35 | ancient | 14 | [Xe] 4f14 5d10 6s2 6p2 | 7.42 | ||
| 83 | 208.980 | Bismuth | Bi | 271 | 1,560 | 9.75 | ancient | 15 | [Xe] 4f14 5d10 6s2 6p3 | 7.29 | ||
| 84 | * | 209.000 | Polonium | Po | 254 | 962 | 9.30 | 1898 | 16 | [Xe] 4f14 5d10 6s2 6p4 | 8.42 | |
| 85 | * | 210.000 | Astatine | At | 302 | 337 | 0.00 | 1940 | 17 | [Xe] 4f14 5d10 6s2 6p5 | 9.30 | |
| 86 | * | 222.000 | Radon | Rn | -71 | -62 | 9.73 | 1900 | 18 | [Xe] 4f14 5d10 6s2 6p6 | 10.75 | |
| 87 | * | 223.000 | Francium | Fr | 27 | 677 | 0.00 | 1939 | 1 | [Rn] 7s1 | 4.07 | |
| 88 | * | 226.000 | Radium | Ra | 700 | 1,737 | 5.50 | 1898 | 2 | [Rn] 7s2 | 5.28 | |
| 89 | * | 227.000 | Actinium | Ac | 1,050 | 3,200 | 10.07 | 1899 | 3 | [Rn] 6d1 7s2 | 5.17 | |
| 90 | 232.038 | Thorium | Th | 1,750 | 4,790 | 11.72 | 1829 | 102 | [Rn] 6d2 7s2 | 6.31 | ||
| 91 | 231.036 | Protactinium | Pa | 1,568 | 0 | 15.40 | 1913 | 102 | [Rn] 5f2 6d1 7s2 | 5.89 | ||
| 92 | 238.029 | Uranium | U | 1,132 | 3,818 | 18.95 | 1789 | 102 | [Rn] 5f3 6d1 7s2 | 6.19 | ||
| 93 | * | 237.000 | Neptunium | Np | 640 | 3,902 | 20.20 | 1940 | 102 | [Rn] 5f4 6d1 7s2 | 6.27 | |
| 94 | * | 244.000 | Plutonium | Pu | 640 | 3,235 | 19.84 | 1940 | 102 | [Rn] 5f6 7s2 | 6.03 | |
| 95 | * | 243.000 | Americium | Am | 994 | 2,607 | 13.67 | 1944 | 102 | [Rn] 5f7 7s2 | 5.97 | |
| 96 | * | 247.000 | Curium | Cm | 1,340 | 0 | 13.50 | 1944 | 102 | 5.99 | ||
| 97 | * | 247.000 | Berkelium | Bk | 986 | 0 | 14.78 | 1949 | 102 | 6.20 | ||
| 98 | * | 251.000 | Californium | Cf | 900 | 0 | 15.10 | 1950 | 102 | 6.28 | ||
| 99 | * | 252.000 | Einsteinium | Es | 860 | 0 | 0.00 | 1952 | 102 | 6.42 | ||
| 100 | * | 257.000 | Fermium | Fm | 1,527 | 0 | 0.00 | 1952 | 102 | 6.50 | ||
| 101 | * | 258.000 | Mendelevium | Md | 0 | 0 | 0.00 | 1955 | 102 | 6.58 | ||
| 102 | * | 259.000 | Nobelium | No | 827 | 0 | 0.00 | 1958 | 102 | 6.65 | ||
| 103 | * | 262.000 | Lawrencium | Lr | 1,627 | 0 | 0.00 | 1961 | 102 | 4.90 | ||
| 104 | * | 261.000 | Rutherfordium | Rf | 0 | 0 | 0.00 | 1964 | 4 | 0.00 | ||
| 105 | * | 262.000 | Dubnium | Db | 0 | 0 | 0.00 | 1967 | 5 | 0.00 | ||
| 106 | * | 266.000 | Seaborgium | Sg | 0 | 0 | 0.00 | 1974 | 6 | 0.00 | ||
| 107 | * | 264.000 | Bohrium | Bh | 0 | 0 | 0.00 | 1981 | 7 | 0.00 | ||
| 108 | * | 277.000 | Hassium | Hs | 0 | 0 | 0.00 | 1984 | 8 | 0.00 | ||
| 109 | * | 268.000 | Meitnerium | Mt | 0 | 0 | 0.00 | 1982 | 9 | 0.00 | ||
| No. | Atomic Weight | Name | Sym. | M.P. (°C) | B.P. (°C) | Density* (g/cm3) | Earth crust (%)* | Discovery (Year) | Group* | Electron configuration | Ionization energy (eV) |
Notes:
• Density of elements with boiling points below 0°C is given in g/l. In a sorted list these elements are shown before other elements that have boiling points >0°C.
• Earth crust composition average values are from a report by F. W. Clarke and H. S. Washington, 1924. Elemental composition of crustal rocks differ between different localities (see article).
• Group: There are only 18 groups in the periodic table that constitute the columns of the table. Lanthanoids and Actinoids are numbered as 101 and 102 to separate them in sorting by group.
• The elements marked with an asterisk (in the 2nd column) have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.
Abbreviations and Definitions:
No. - Atomic Number
M.P. - melting point
B.P. - boiling point
Atomic number: The number of protons in an atom. Each element is uniquely defined by its atomic number. Affinity designer beta 1 7 0 57 ver5 plugin.
Noteburner m4v converter plus sn 4 1 6 download free. Atomic mass: The mass of an atom is primarily determined by the number of protons and neutrons in its nucleus. Atomic mass is measured in Atomic Mass Units (amu) which are scaled relative to carbon, 12C, that is taken as a standard element with an atomic mass of 12. This isotope of carbon has 6 protons and 6 neutrons. Thus, each proton and neutron has a mass of about 1 amu.
Isotope: Atoms of the same element with the same atomic number, but different number of neutrons. Isotope of an element is defined by the sum of the number of protons and neutrons in its nucleus. Elements have more than one isotope with varying numbers of neutrons. For example, there are two common isotopes of carbon, 12C and 13C which have 6 and 7 neutrons respectively. The abundances of different isotopes of elements vary in nature depending on the source of materials. For relative abundances of isotopes in nature see reference on Atomic Weights and Isotopic Compositions.
Atomic weight: Atomic weight values represent weighted average of the masses of all naturally occurring isotopes of an element. The values shown here are based on the IUPAC Commission determinations (Pure Appl. Chem. 73:667-683, 2001). The elements marked with an asterisk have no stable nuclides. For these elements the weight value shown represents the mass number of the longest-lived isotope of the element.
Electron configuration: The distribution of electrons according to the energy sublevels (subshells) in uncharged atoms. The noble gas shown in square brackets (e.g. [He]), marks that all the subshells associated with that element are fully occupied by electrons.
| Principal energy level (Quantum number: n) | Sublevels available (Quantum number: l) |
| 1 2 3 4 5 6 | 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 5g 6s 6p 6d 6f 6g 6h |
Ionization energy (IE): The energy required to remove the outermost electron from an atom or a positive ion in its ground level. The table lists only the first IE in eV units. To convert to kJ/mol multiply by 96.4869. Reference: NIST Reference Table on Ground states and ionization energies for the neutral atoms. IE decreases going down a column of the periodic table, and increases from left to right in a row. Thus, alkali metals have the lowest IE in a period and Rare gases have the highest.
Other resources related to the Periodic Table
- Chemical Evolution of the Universe
