Chemistry - Chemical patterns

Isotope

Variations of a chemical element that has the same number of protons but different number of neutrons.

Ground state

Normal electron configuration of atoms.

Excited state

When an electron temporarily occupies an energy state greater than its ground state.

Cation

Atoms that have lost electrons in order to achieve a stable valence shell. Positively charged. Metals

Anion

Atoms that have gained electrons in order to achieve a stable valence shell. Negatively charged. Non-metals

Groups

Number of electrons in the valence shell.

Period

Number of shells.

Compound

A substance that contains two or more different elements.

Molecular compound

Made up of non-metals that covalently bond.

Elemental molecules

Made up of one kind of non-metal.

Element

Pure substance only made up of one type of atom.

Molecule

Two or more atoms that are chemically bonded together.

Covalent bonding

A chemical bond where atoms share electron pairs in order to receive a stable electrons configuration.

Ionic bonding

A chemical bonding that involves electrostatic attraction between oppositely charged ions.

Lattice

A structure with particles arranged in a repeating pattern.

Metallice bonding

A chemical bond that occurs between positively charged metal atoms and the sea of electrons that glue them together.

Delocalised

Freely moving.

Ductilablity

The ability of a material to be stretched into a thin wire without breaking

Malleability

The ability of a material to be hammered or pressed without breaking.

Properties of metallic bonding:

• high melting points

• good conductors of heat and electricity

• malleable

• ductile

• lustrous

Properties of ionic bonding:

• brittle

• high melting points as solids

• don’t conduct electricity as solids

• do conduct electricity when dissolved in water as ions are free to move

Properties of covalent bonding:

• low melting and boiling points

• poor conductivity

• varying solubility

Alloys

Mixture of metals