Basic Atomic Structure and Isotope Concepts for Chemistry

Atom

The smallest particle of an element that retains the properties of that element.

Proton

A positively charged subatomic particle.

Electron

A negatively charged subatomic particle.

Neutron

A subatomic particle with no charge.

Nucleus

The central part of an atom, containing protons and neutrons.

Isotopes

Atoms with the same number of protons, but different numbers of neutrons.

Mass number

The total number of protons and neutrons in the nucleus.

Atomic number

The number of protons in the nucleus of an atom.

Average atomic mass

Weighted average of the masses of the isotopes of an element.

Atomic mass unit (amu)

Unit used to measure the mass of an atom.

Neutral

All atoms are neutral, with the number of protons equaling the number of electrons.

Protons and neutrons

The particles that are found in the nucleus of an atom.

Atomic number of an element

The total number of protons in the nucleus.

Mass number representation

The number 84 in the name krypton-84 represents the mass number.

Neutrons in ¹⁶O

8

Protons, electrons, and neutrons in atom

50 protons, 50 electrons, 75 neutrons.

Isotopes of the same element

Have different numbers of neutrons and different mass numbers.

Calculate number of neutrons

Subtract the number of protons from the mass number.

Hydrogen-1 and hydrogen-2

Hydrogen-2 has one neutron; hydrogen-1 has none.

Group B elements

Another name for the transition metals.

Average atomic mass calculation

Multiply each isotope's mass by its relative abundance and add the results.

Average atomic mass of boron

10.7 amu.