| A | B |
|---|
| element | a pure substance that cannot be broken down into simpler substances |
| compound | a pure substance that is composed of two or more atoms |
| atom | the smallest particle of any element that retains the properties of the element |
| chemical changes | changes in the ways the atoms in a pure substance are arranged |
| subatomic particles | particles that make up an atom |
| protons | subatomic particles with a positive charge |
| neutrons | subatomic particles with no electric charge |
| electrons | subatomic particles that have a negative charge |
| nucleus | centre of an atom made of protons and neutrons |
| nuclear charge | electric charge of the nucleus |
| period | horizontal row on the periodic table |
| group | vertical column on the periodic table |
| alkali metals | Group 1: very reactive metals |
| alkaline earth metals | Group 2: reactive metals |
| halogens | Group 17: very reactive non-metals |
| noble gases | Group 18: inert gaseous non-metals |
| transition metals | Groups 3-12 on the periodic table |
| family | group of chemicals that have similar chemical properties |
| ions | electrically charged particles |
| cations | positively charged ions. Formed with atoms lose electrons |
| anions | negatively charged ions. Formed with atoms gain electrons |
| multivalent | form ions in more than on way |
| Bohr diagram | shows how many electrons are in each shell |
| stable octet | arrangement of eight electrons in the outermost shell |
| valence shell | the outermost shell that contains electrons |
| valence electrons | electrons in the outermost shell |
| ionic bond | bond where electrons are transferred |
| covalent bond | bond where electrons are shared |
| covalent compound | compound formed when non-metallic atoms share electrons |
| molecule | a group of atoms that are bond together by sharing electrons |
| bonding pair | pair of electrons that are involved in a covalent bond |
| lone pair | pair of electrons in the valence shell that is not used in bonding |
| Lewis diagram | shows only an atom's valence electrons |
| diatomic molecule | a pair of atoms of the same element joined by covalent bonds |
