Chemistry Test 1

Types of chemical bonds

Ionic
Covalent
Metallic

If an atom gains electrons what charge does it have

Negative

Calcium is in group 2 of the periodic table. What happens to a calcium atom when it becomes an ion?

Because calcium is a Group 2 metal, there are 2 electrons in its outer shell.
Calcium atoms remove these 2 electrons to achieve a full outer shell containing 8 electrons, and in doing so become Ca2+ ions.

Ionic Bondings are made up of

Metal + non-metal

Materials with ionic bonds usually

Have high melting points
Only conduct electricity when molten/dissolved

Covalent bonding involves 2 atoms sharing 1 or more pairs of

electrons

If an ion is positive, it has less electrons than

protons

What do atoms have the same amount of

Protons
Electron

Covalent bonds are made up of

Non-metals only

Metallic bonds are made up of

Metals only

why can't ionic compunds carry an electric current

the ions are fixed in place

covalent bondings have

occurs between two non-metals

the electrons are shared

they do not involved charged particles

ionic bondings have

involves charged particles

occurs between metal and non-metal atoms

electrons are lost or gained / transferred

covalent bonds do not conduct electricity due to

mobile charge carriers (e.g delocalised electrons or ions)

why does propane have a low boiling point

the intermolecular forces are weak

all bonds are aiming for

a full outer shell of electrons for stability

metallic bondings have

there is a sea of delocalised electrons

involves an electrostatic force

can conduct electricity

surface area =

height * width * n(sides)

volume =

base * height * width

are ionic and covalent bonds made up of metals and non-metals

no ionic takes a mix

with Mg3- Cl2+ what can you do to balance them

swap the numbers around e.g Mg2Cl3

what is the big ionic compound of sodium and chlorine atoms called

a giant ionic lattace

what is needed for the ionic compound of sodium chloride to conduct electricity

it needs to be molten or dissolved because the charged ions are attracted to the water ions

they also need to be mobile and free moving

why does potassium chloride have a high melting point

the electrostatic force of attraction between the ions is very strong and require a lot of energy to break

one pair of shared electrons is equal to

one covalent bond

two ways to indicate a covalent bond

H-H a solid line and a dot and cross diagram

properties of SMALL covalent molecules

do not conduct electricity (delocalised electrons)

low boiling point (intermolecular forces)

also the covalent bonds do not break

properties of diamond

high boiling/melting point

doesn't conduct electricity

and is hard

it forms 4 bonds

properties of graphite

high boiling/melting point

conducts electricity

is soft

it forms 3 bonds

why is diamond hard

because the carbon atoms are held strongly together with strong covalent bonds

why is graphite soft

because it is made up of layers of carbon atoms that slide over eachover

why can graphite conduct electricity and diamond can not

because they have delocalised electrons that slide over eachover

what can you use graphene for

anything to do with electricity like a wire

properties of graphene

made from a single layer of graphite

high melting point

it is strong

can conduct electricity

what can buckminister fullerenes be used for

for drug delivery into the body

what can carbon nanotubes be used for

what can graphite be used for

lubricants

what type of shape do fullerenes have

hollow/spherical

why are alloys harder than pure metals

a greater force is required for the layers to slide over each other

properties of carbon nanotubes

high elasticity high thermal conductivity low density

why can anything conduct electricity

DELOCALISED ELECTRONS

an alloy is a metal which

has different types/sizes of atoms

what if something has strong covalent bond

often form molecules, with low melting and boiling points, such as hydrogen and water

what is difference between an ionic and covalent bond

In ionic bonding, one atom donates electrons to the other In covalent bonding, the two atoms share electrons