Mass number is the number of protons and neutrons in the nucleus of an atom.
Atomic number is the number of protons (or electrons) in an atom
An isotope is an element with a different mass number as they have the same number of protons but different number of neutrons
The relative atomic mass is the average mass of an atom of an element
The number of particles is found by multiplying the number of moles by avogadros constant
Empirical formula is the simplest whole number ratio of particles in a compound
Molecular formula is the true number of atoms in a compound
Percentage composition is found by dividing the Mr of the element by the Mr of the compund x 100
n = cv
mass = Mr x n
Making a solution:
Weigh sample bottle with sample in on a balance 2d.p.
Transfer sample to beaker and reweigh bottle
Record difference in mass
Add distilled water and stir with glassrod until fully dissolved
Transfer to volumetric flask and rinse beaker
Make up to 250cm3 mark with distilled water and invert several times
There are different orbitals in shells: s, p, d and f. The s-orbital is spherical and the p-orbital is dumbbell shaped
Electrons in shells:
s = 2
p = 6
d = 10
f = 14
Chromium and Copper are the two exceptions:
Chromium is 3d5 4s1 half is more stable
Copper is 3d10 4s1 full is more stable
Fusion is when twolighter nuclei fuse to make one heavier nuclei
Ionic bonding is an electrostatic attraction between two postive and negative ions and happens between a metal and non-metal. They canconduct electricity but only when molten or aqueous as ions can move
Oppositely charged ions form electrostatic attractions and form a giant ionic lattice
A covalent bond is an electrostatic attraction between two non-metals and can form multible bonds when multiple electrons are shared
Dative covalent bonds are formed when the electrons in the bond are both from the same atom
Linear molecules have 2 bonding pairs and a bond angle of 180º
Bent molecules have 2 bonding and 1 lone pair and a bond angle of 104.5º
Trigonal planar molecules have 3 bonding pairs and a bond angle of 120º
Trigonal pyramidal molecules have 3 bonding and 1 lone pair and a bond angle of 107º
Tetrahedral molecules have 4 bonding pairs and a bond angle of 109.5º
Trigonal bipyrimidal molecules have 5 bonding pairs and bond angles of 90º and 120º
Octahedral molecules have 6 bonding pairs and a bond angle of 90º
Giant covalent structures like diamond (4 C-C bonds) and graphite (3 C-C bonds) are very strong and have high melting points
Intermolecular forces between graphite layers are weak to they can slide over each other and therefore is useful as a lubricant
Diamond is a tertahedral structure which is why it's so strong
Metallic bonding is between two metals and is a giant lattice of strongly attracted electrons with a sea of delocalised electrons The greater the charge the stronger the attractive forces
Ions that have a larger atomic radius have a weaker attraction
Metallic structures are good at conducting electricity as the delocalised electrons can carry a charge
Metals are malleable because the layers can slide over each other and they also have high melting points due to the electrostatic forces
Melting points increase across a period and decrease down a group which is due to the type of bonding within the elements
Group 2 carbonates are more thermally stable as you go down the group
A higher charge density will result in a higher distorting effect on neighbouring negative ions in group 2 carbonates
Solubility of group 2 carbonates decreases down the group
Solubility of group 2 hydroxides increases down the group
Ionisation energy increases across a period due to decreasing atomic radius but decreases down a group due to increasing atomic radius