Bionic bonding[1]
Magnesium is a metal and oxygen is a non-metal. Magnesium loses 2 electrons and oxygen gains them, so ions form and attract each other.
Bgraphite[1]
Each carbon atom in graphite uses only 3 of its 4 outer electrons, so one electron per atom is free to move.
BEach carbon atom is bonded to four others by strong covalent bonds.[1]
A large amount of energy is needed to break the many strong covalent bonds in the giant network.
B2[1]
Each oxygen atom has 6 outer electrons and shares 2 of them. This makes a double bond, which is two shared pairs.
A sodium atom loses 1 electron to form a sodium ion, Na+. [1]
A chlorine atom gains 1 electron to form a chloride ion, Cl−. [1]
Ionic bond. [1]
It is the electrostatic attraction between the oppositely charged ions. [1]
Bphosphorus and oxygen[1]
Covalent bonds form between non-metals. Phosphorus and oxygen are both non-metals. The other pairs are a metal and a non-metal, which form ionic bonds.
Aelectrostatic forces of attraction between positive metal ions surrounded by a ‘sea of delocalised electrons’[1]
Metal atoms lose their outer electrons to form positive ions. The attraction between oppositely charged particles is electrostatic.
ACopper has a ‘sea’ of delocalised electrons.[1]
The delocalised electrons are mobile charge carriers. The positive ions stay in fixed positions.
DCa3(PO4)2[1]
Calcium forms Ca2+ and phosphate is PO43−. Three Ca2+ (+6) balance two PO43− (−6).
Cgiant ionic structure, because it has free-moving ions[1]
The ions are fixed in the solid but move freely when dissolved.
Bair, tungsten, sodium bromide[1]
Tungsten is a metallic element, sodium bromide is an ionic compound and air is a gaseous mixture. The order in the list does not matter.
DD[1]
In D, atoms of two different elements join to form particles of a new compound, so a new substance is made.
CIn an alloy there is attraction between positive ions and a ‘sea of delocalised electrons’.[1]
An alloy still has metallic bonding. It can contain a non-metal, as steel contains carbon, and it is a mixture, so brass has no chemical formula.
Sodium sulfate [1]
Graphite [1]
Sulfur dioxide and sodium sulfate [1]
Both contain sulfur and oxygen.
Dry ice [1]
Graphite [1]
Any one: dry ice, CO2 or sulfur dioxide, SO2 or sodium sulfate, Na2SO4. [1]
Correct number of electrons: a nitrogen atom with 3 shared pairs and 1 lone pair, and each hydrogen atom with 1 shared pair. [1]
Correct number of atoms: one nitrogen atom bonded to three hydrogen atoms. [1]
A giant metallic structure, a lattice of positive ions [1]
in a sea of delocalised electrons. [1]
Sc2(SO4)3 [1]
Sc2O3 shows that scandium forms Sc3+ and sulfate is SO42−.
Sc(OH)3 [1]
The correct ratio of two Li+ ions to one O2− ion. [1]
Each ion shown with its charge: Li+ with no outer electrons and O2− with 8 outer electrons, in square brackets. [1]
Li2O: solid [1]
CH4: gas [1]
Li2O has a giant ionic lattice. [1]
As a solid, the ions are held in fixed positions and cannot move freely to conduct electricity. [1]
CH4 consists of simple molecules. [1]
The weak intermolecular forces of attraction need little energy to overcome, so the melting and boiling points are low. [1]