OCR Gateway GCSE Chemistry A Elements, compounds and mixtures (C2) overview quiz quiz

Electrons are transferred from the metal to the non-metal

Electrons are shared equally between the two bonded atoms

Electrons are delocalised across the whole giant structure

Electrons are destroyed completely as the new bond forms

MgCl

MgCl2

Mg2Cl

Mg2Cl3

The strong covalent bonds inside each of the molecules are actually very weak

They have a sea of delocalised electrons spread throughout the structure

Only the weak forces between molecules need to be overcome to melt or boil them

They are giant lattice structures held together by strong bonds in all directions

Graphite contains charged ions that are free to move and carry the current

Diamond is a mixture of different substances rather than a pure element

Graphite is actually a metal, which is the reason why it can conduct an electric current

Each carbon in graphite has a delocalised electron, but diamond has no free electrons

The delocalised electrons are free to move and carry charge

The positive metal ions move through the lattice and carry the charge

The neutrons break free and move through the whole metal structure

The metal contains free-moving ions dissolved in a solution inside it

The atoms that are added in make the metal much lighter and less dense overall

The different-sized atoms distort the regular layers, so they cannot slide as easily

The alloy has far stronger metallic bonds acting equally in every single direction

The alloy contains no delocalised electrons at all, so the layers are locked rigidly

Magnesium oxide is held together by strong covalent bonds, not ionic ones

Sodium chloride is actually a metal, so its bonds are easier to break apart

Its ions (2+ and 2-) are more highly charged, so the electrostatic attraction is stronger

Magnesium oxide is only a simple molecule that has very weak forces between the molecules

It decreases

It stays the same

It becomes zero

It increases

A pure substance melts at a single, fixed temperature; a mixture melts over a range

A pure substance melts over a wide range of temperatures while a mixture stays sharp

A pure substance does not melt at all, no matter how strongly it is heated up

Purity cannot be tested using melting point because every substance behaves alike

4.0

0.25

0.36

9.0