Chemistry test revision

What is an ionic bond?

What is an ionic bond?

An ionic bond is the electrostatic attraction of ions with opposite charges

what is electro valency?

It is the charge associated with a particular ion

What is the ionic formulae?

The formula of an ionic compound can be found by balancing the charges on the ions. The overall charge on an ionic compound is zero.

What is a Polyatomic ion?

A polyatomic ion is a group of tightly bound atoms that behaves as a single unit and carries an overall charge (most are anions).

What are the properties of an ionic compound?

They have high melting and boiling points because the electrostatic forces of attraction between the ions are strong and large amounts of energy are needed to separate the ions

Metal ions

•       Metals atoms tend to lose electrons.

•       This means that metals will form positive ions (by losing electrons) known as cations.

•       A metal atom will tend to lose all electrons contained in the valence shell of the atom.

•       Reactive metals lose the outer shell electrons more easily.

metallic bond

is the electrostatic attraction of cations and delocalised electrons.

The metallic bonding model

Many metallic cations come together to form a lattice structure held together by the valence electrons lost from the atoms

List heat treatments

Annealing, quenching, tempering

Annealing

Metals are heated until they are red hot and then allowed to cool slowly.

·       What size crystals will form?                            large

·       How many gaps will there be between crystals?  few

·       Which properties will the metal now have?         softer    and malleable

Quenching

Metals are heated until they are red hot and then forced to cool quickly in cold water.

·       What size crystals will form?                            small

·       How many gaps will there be between crystals?  many

Which properties will the metal now have?          harder  and       brittle

Tempering

Metals are produced when quenched metals are warmed again to a lower temperature and then allowed to cool slowly.

·       What size crystals will form?                            medium

·       How many gaps will there be between crystals?  some

This procedure reduces the brittleness of the metal while retaining the hardness

what is an alloy?

An alloy is a mixture of two or more elements, where at least one element is a metal, and the resulting material has metallic properties.

what is a Pure metal?

Is metal comprised of one type of atom only

what is a Covalent bond?

A covalent bond is a type of chemical bond where two atoms share one or more pairs of electrons.

What is a molecule?

A molecule is a group of two or more atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.

Naming molecule?

for each element in the molecule depending on the number of the element you put an add on to the name: 1 (mono but you dont really need to use it), 2 (di), 3 (tri), 4 (tetra), 5 (penta), 6 (hexa)

What must a substance contain to conduct electricity?

free moving/mobile charged particles

Electrostatic attraction

Electrostatic attraction is the force that pulls opposite charges toward each other, such as the attraction between positively charged protons and negatively charged electrons.