Table of Contents
Atomic Mass of Elements
The atomic mass is the mass of an atom of that element relative to the mass of a carbon-12 atom. It is expressed in unified atomic mass units (u).
The atomic mass of an element is the mass of an atom of the element relative to the mass of a carbon-12 atom. It is measured in atomic mass units (amu). The atomic mass of an element can be found on the periodic table.
The atomic mass of an element can be used to determine the mass of a molecule of the element. To do this, the atomic mass of the molecule is divided by the atomic mass of the element. This gives the mass of the atom in the molecule.
The Periodic Table
The Periodic Table of Elements is a table that arranges all the known elements in order of atomic number. The atomic number is the number of protons in an element’s nucleus. The elements are arranged in groups and periods. Groups are vertical columns and periods are horizontal rows.
- The first group, Group 1, consists of alkali metals. These are the elements with one electron in their outermost energy level. The second group, Group 2, consists of alkaline earth metals. These are the elements with two electrons in their outermost energy level.
- The third group, Group 3, consists of the transition metals. These are the elements with partially filled energy levels. The fourth group, Group 4, consists of the carbon group. These are the elements with four electrons in their outermost energy level.
- The fifth group, Group 5, consists of the nitrogen group. These are the elements with five electrons in their outermost energy level. The sixth group, Group 6, consists of the oxygen group. These are the elements with six electrons in their outermost energy level.
- The seventh group, Group 7, consists of halogens. These are the elements with seven electrons in their outermost energy level. The eighth group, Group 8, consists of noble gases. These are the elements with eight electrons in their outermost energy level.
Atomic Number
The atomic number of an element is the number of protons in the nucleus of an atom of that element.
Atomic Number of Elements from 1 to 30
Here is a table of the approximate atomic masses of the first 30 elements:
| Element | Atomic Mass (in amu) |
|---|---|
| Hydrogen | 1.008 |
| Helium | 4.0026 |
| Lithium | 6.94 |
| Beryllium | 9.0122 |
| Boron | 10.81 |
| Carbon | 12.011 |
| Nitrogen | 14.007 |
| Oxygen | 15.999 |
| Fluorine | 18.998 |
| Neon | 20.180 |
| Sodium | 22.990 |
| Magnesium | 24.305 |
| Aluminum | 26.982 |
| Silicon | 28.085 |
| Phosphorus | 30.974 |
| Sulfur | 32.06 |
| Chlorine | 35.453 |
| Argon | 39.948 |
| Potassium | 39.098 |
| Calcium | 40.078 |
| Scandium | 44.956 |
| Titanium | 47.867 |
| Vanadium | 50.942 |
| Chromium | 51.996 |
| Manganese | 54.938 |
| Iron | 55.845 |
| Cobalt | 58.933 |
| Nickel | 58.693 |
| Copper | 63.546 |
| Zinc | 65.38 |
Please note that these atomic masses are approximate values and may vary slightly depending on the isotopic composition of the element.
Isotopes
The iodine element has six naturally occurring isotopes, I-123, I-124, I-125, I-126, I-127, and I-128. There are five artificial radioactive isotopes, I-129, I-130, I-131, I-132, and I-133.
Atomic Mass
The atomic mass is the mass of one atom of that element. It is expressed in atomic mass units (AMU).
Difference Between the Atomic Number and the Atomic Mass of Elements
The atomic number of an element is the number of protons in its nucleus, while the atomic mass is the total mass of the protons and neutrons in the nucleus.
