U4 Chemistry

Page 1

Particle theory

Key words

Distillation:

Impure solvent - what is put in at the beginning of distillation

Leibig condenser - condenser in distillation

Filtration

Residue - substance left in filter paper

Filtrate - substance which goes through funnel

Chromatography

Differential - Showing a difference, distinctive

Stationary Phase - Part of apparatus, doesn't move with sample

Affinity - Natural attraction or force between things

Mobile Phase - Liquid or gas that carries component

Other

Solute - Solid chemical - is dissolved

Solvent - Chemical liquid - dissolves another chemical

Solution - Mixture of solute and solvent

Distillation

2 types of distillation

Simple distillation - Separates 1 liquid

Fractional distillation - Separates a mixture of liquids

Method

Heat solution in flash, it evaporates, steam rises to condenser, salt is left behind.

Condenser is cold (water jacket), steam condenses

Water drips into beaker - distilled water

http://www.docbrown.info/page12/gifs/distill.gif

Crystallisation

Soluble liquids can be separated

Method

Solution is heated - get rid of some solvent

As solvent evaporates, solution more concentrated

Solution can be checked to see if ready - place drop of solution on microscopic slide

Solution is left to cool and crystallise

Crystals are filtered, rinsed and dried

Filtration

Separates insoluble solids from liquid

Residue gets left in paper, filtrate goes through paper

http://www.micromountain.com/sci_diagrams/sci_app/sci_app_assets/filter_lab_eng.jpg

Chromatography

Used to identify, analyse, purify and/or quantify a mixture of components

Some particles travel further than others -different solubility / attractions

RF ( retention factor )

Used to compare components of various samples

Distance from past line to the spot ÷ distance from the base line to the solvent front

Always less than 1

States of matter

solid -----> liquid = melting

liquid -----> gas = evaporation

gas -----> liquid = condensation

liquid -----> solid = freezing

solid -----> gas = sublimation

Page 2

Atomic structure

3 particles in an atom:

protons

neutrons

electrons

| Atomic particle | Relative mass | Relative charge |

| Protons | 1 | +1 |

| Electrons | 1 | -1 |

| Neutrons | 1/2000 (0.0005) | 0 |

Structure of an atom

Protons and neutrons are in the nucleus

Electrons are in the shells around nucleus

Number of electrons and protons are the same (unless bonded)

Mass number - total number of protons and neutrons (mass of atom)

Atomic number (number below element symbol) - number of protons in an atoms nucleus

Relative mass (number above element symbol) - ✩✩ FIND ANSWER

Number of neutrons = mass number - atomic number

Isotopes - atoms containing same number of protons, different number of neutrons

Group number - number of outer shell electrons

Period number - number of electric shells

RAM (relative atomic mass) = (mass number of atom 1 x percentage of atom 1) +

(mass number of atom 2 x % of atom 2) + etc

(÷) divided by --------------------------------------------------------------------------

100

(will get given %)

Page 3

Periodic Table

Balancing Equations

Write correct formula of each substance

Balance number of atoms (of each element) by putting a BIG NUMBER IN FRONT of formula

Check both sides of equation to see if there are same number of atoms each element on both sides of equation

NEVER CHANGE SMALL NUMBER WHEN TRYING TO BANCE AN EQUATION

Number of atoms must be same on both sides

Subscript (small) number only multiplies thing it's attached to

Big

((s2) = small 2)

Eg

Sodium + Chlorine > Sodium chlorid

2Na + Cl(s2) > 2NaCl

Potassium + Oxygen > Potassium oxide

4K + O(s2) > 2K(s2)O

Vertical columns - groups

Horizontal columns - periods

Group number - number of outer shell electrons

Period number - number of electron shells

Diatomic Elements - Elements which come in pairs (small 2 at bottom)

H2

N2

O2

F2

Cl2

Br2

I2

Group 1 (Alkali metals)

Soft metals (get softer as you go down)

Dull grey colours (oxidisation)

When heated in air, group 1 metals react with oxygen - forms metal oxide

Eg

Word equation : Sodium + Oxygen → Sodium Oxide

Chemical equation : 4Na + O2 → 2Na2O

Density of water - 1g/cmº2

General word equation:

GROUP 1 METAL + WATER → METAL HYDROXIDE + HYDROGEN GAS

Eg

Lithium + water → Lithium hydroxide + hydrogen

2Li + 2H2O → 2LiOH + H2

Group 7 (Halogens)

Less reactive going down group

Group 7 elements are referred to as DIATOMIC non-metals

Diatomic molecule - molecule consisting of 2 atoms chemically combined