Chemistry revision

Mass number

larger number

Atomic Number

smaller number (number of protons)

Neutrons

mass number - atomic number

Isotopes

are different forms of the same element

element

substance made up of one type of atom

Compound

Substance formed from more than one element

Molecule

A group of two or more atoms

Mixture

Combination of two or more things which are not chemically bond

Lattices

Atoms bound together to form repeating structures

Crystal lattices

Have a particular shape

Ions

Atoms with unequal numbers of protons and electrons

Cation

An atom with a positive charge

Anion

An atom with a negative charge

Vertical columns are called

groups

horizontal rows are called

periods

Valency

A measure of the combining power of an atom.

How is valency determined?

The valency of an element is determined by the number of electrons in its outermost shell

What do groups tell us?

The number of valence electrons.

What do periods tell us?

The number of occupied electron shells.

Properties of metals are..

Lustrous, conductors of heat and electricity, malleable, ductile and solid at room temperature.

Properties of non-metals are…

Poor conductors of heat and electricity, brittle, low melting and boiling points and are dull.

Properties of metalloids are…

Act like non-metals in most ways. They are semi conductors.

What are alloys?

Metals combined with small amounts of another element.

What are alloys used for?

Tooth fillings, aircraft frames, joining metals together, electrical connections and paperclips.

What are atoms made up of?

Protons, neutrons and electrons

What is the center of an atom?

The nucleus

What does the nucleus contain?

Protons and neutrons

Where is most weight contained?

In the nucleus

Metallic lattices

Don’t have a set shape

Groups are the……..

number of valence electrons

Periods are the……..

number of occupied electron shells

What is the difference between anions and cations?

Anions gain electrons and cations loose electrons

Isotopes are…

atoms of the same element that have the same number of protons and electrons but different numbers of neutrons.