c3 Flashcards
define element
contains only one kind of atom
define compound
contains two or more kinds of atoms, typically chemically bonded
explain the structure of metallic elements
-strong metallic bonds hold the metal atoms in a lattice.
-no molecules, hence no intermolecular forces.
describe the atoms in group 8 (or group 0)
- exist as individual atoms only.
- dont bond with other atoms as they already have a full outer shell.
- weak intermolecular forces between the atoms.
describe the atoms in group 7
-diatomic molecules
-strong covalent bonds joining one Cl to the other, but weak intermolecular forces between the Cl2 molecules.
what are the other diatomic molecules that aren’t in group 7?
N2, O2 and H2
what happens in ionic bonding?
metal + non metal
give/takes electrons
what happens in covalent bonding?
non metal + non metal
shares electrons?
what happens in alloy mixture?
metal + metal
explain atom
smallest particle of an element
have a nucleus containing protons and neutrons
electrons orbit in shells
define molecule
particle consisting of two/more non-metal atoms joined by covalent bonding.
what is the chemical formula of hydrochloric acid?
HCO
what is the chemical formula of nitric acid?
HNO3
what is the chemical formula of methane?
CH4
what is the chemical formula of water?
H20
what is the chemical formula of ammonia
NH3
what is the chemical formula of sulfuric acid?
H2SO4
how much charge is there for each group on the periodic table? and how do you work it out?
group 1 - +1
group 2 - +2
group 3 - +3
(group 4 usually doesn’t form ions)
group 5 - 3-
group 6 - 2-
group 7- 1-
the group number is equal to how many electrons there are in the outermost cell, and the charge is dependent on how many they have to lose or gain to have a full outer shell.
how do you write ionic formulae?
you need to balance the charges on the ions so that the total is 0
you may need to add a subscript number and use brackets for compound ions
what is the law of conservation of mass?
-atoms can’t be created or destroyed by chemical reactions
-the same atoms are present at the start and end of a reaction, they are just rearranged to form different substances
-the total mass stays the same
how can you investigate conservation of mass?
in a closed system (where no substances can enter/leave during the reaction)
what are the two ways that you can investigate conservation of mass?
-a beaker if the reactants are in solution and no gases are formed
-a flask attached to a gas syringe to stop gases produced from escaping.
why can the mass appear to change?
if you don’t have a closed system, then the mass can appear to change
why could the mass descrease?
if a gas is produced and escapes the mass can appear to decrease
