Chap 1 (atomic structure)

Element

A substance containing only one type of atom. All the atoms in an element have the same proton number

Atom

The smallest part of an element that can take part in a chemical change. Every atom contains protons in its nucleus and electrons outside the nucleus. Most atoms have neutrons in the nucleus except isotope of hydrogen 1.

Proton

A positively charged particle in the nucleus of the atom. With a +1 charge

Neutron

Uncharged particle in the nucleus of an atom with the same relative mass as a proton. 0 charge

Electron

Negatively charged particle in the nucleus of an atom. It has a negligible mass compared with a proton. With a charge of -1

Energy levels

The specific distances from the nucleus corresponding to the energy of the electrons. Electrons in energy levels further from the nucleus have more energy than those closer to the nucleus. Energy levels are split up into sub-levels which are given the names s, p, d, etc

Atomic number

The number of protons in the nucleus of an atom. Also called the proton number

Isotope

Atoms of the same element with different mass numbers

Mass number

The number of protons + neutrons in an atom. Also called the nucleon number