OCR AS CHEMISTRY A UNIT 1 F321

Amount of substance and the mole: n=m/M

n=Amount of substance m=mass(g) M=Molecular mass

Mole and Gas Volume- Molar Volume- Volume per mole of a gas

V(dm3)  n=V/24      V(cm3)  n=V/24000

Moles and solutions- Standard solution-Solution of known concentration

Moles and Reactions- Stoichoimetry-Molar relationship between the relative quanties of substances taking part in a reaction

How to work out how many atoms there are?

n=m/M=

6.02xn= ansx10^23

top number of element is the mass number(protons and neutrons)

Bottom number atomic number (protons)

Proton: Relative mass=1 Charge=+1        Neutron:Relative mass=1 Charge=0

Electron:Relative mass=1/2000 Charge= -1

Isotopes-Atoms of the same element with different number or neutrons.

Relative Atomic mass- Weighted mean mass of atom compared with 1/12th of 12g of a atom of C-12

Relative isotope mass- mass of an isotope compared with 1/12th of 12g of a atom of C-12.

Ar=(53/100 x 79)+(47/100 x 81)=79.94

Emperical -simpliest whole number ratio of atoms in each element

Molecular-Actual number of atoms of each element

Emperical Formula Example:

Mg:Br 

0.6075:3.925

0.025:0.050

1:2

Molecular Formula example: Emperical formula:CH2= 12+2=14

No of CH2 in molecule=56/14=4

Molecular Formula=(4xCH2)=C4H8

Acid:-Proton Donor

Base:-Proton Acceptor

Alkali:-Type of Base that dissolves in water to form OH- ions

Salt: Compound formed by Replacing H+ ion in the acid with a metal ion

Cation: Postively charged ion

Anion: Negatively charged ion

Acid+Base->Salt +H2O

Acid+Alkali->Salt+H2O

Acid+Carbonate->Salt+CO2+H2O

Formula: mass of a single element/molecular mass x100 =Percentage of element

Hydated- Crystalline compound containing water molecule

Anhydrous:Crystalline compound containing no water molecules

Water Crystallisation: Water essential to crystalise structure of compound

Working it out: Mass of Hydrated salt Mg.XH2O=4.312g - Mass of MgSO4=2.107g

=mass of H2O=2.205g

Mr:MgSO4=120.4 n=m/M- 2.107/120.4=0.0175mol

n(H2O)=2.205/18=0.1225mol

0.0175:0.1225 = 1:7 = MgSO4.7H2O

Formulas needed to know:

M=m/n              n=m/M                            n=cxV/1000       c=(nx1000)/ V

REACTANTS-->PRODUCTS

Species: Any type of particle which takes place in a chemical reaction

Oxidation Is Loss Reduction Is Gain

Reduction-Gain of Electrons/Decrease in oxidation number

Oxdation-Loss of Electron/Increase in Oxidaton number

Oxidation no- Measure of electrons that an atom uses to bond with atoms of another element

First Ionisation energy- Energy required to remove one electron from each atom of gaseous atoms to for one mole of +1 ions

Orbitals can only hold 2 Electrons

s-orbital 2 electrons in each shell sphere shape

p-orbitals 6 electrons 3 dumbel shape orbitals

d-orbital 10 electrons 5 d orbiatls

f-orbital- 14 electrons 7 f orbitals

ns^e

n=number of orbital(shell number) s=shell that it is in (type of orbital)

^e=number of electrons in shell

Measure of attraction between bonded atoms

Intermolecular forces: 1)IONIC&COVALENT 2)HYDROGEN 3)DIPOLE 4)VAN DER WAALS

Electronegativity