Atomic structure

An atom

The smallest part of an element that can exist

Element

A substance made of only one type of atom

Compound

A substance containing two or more elements chemically combined in fixed proportions

Mixture

A combination of two or more different elements or compounds that are not chemically combined

Filtration

Separate solutions or a solvent from insoluble solids

Crystallisation

Separate soluble solids from water or other solvents

Distillation

Separates a solvent (liquid) from a soluble solid (or two different solvents)

Chromatography

Separate soluble substances

Plum Pudding Model

J.J Thomsons model of an atom, in which he thought electrons were randomly distributed within a ball of positively charged

Nuclear Model

Ernest Rutherford's model of an atom describing a dense positive nucleus around which negative electrons appear to occupy a large amount of space

The alpha particle scatter experiment

- most of the alpha particles passed through the foil

-some particles are deflected as they pass through

-Few particles are completely reflected by the foil

1. most of the atom is empty space

2. The charge must be positive but in a tiny nucleus at the centre.

3 the nucleus must hold most of the mass of the atom

Bohr/planetaru Model

model of an atom that shows electrons in circular orbits around the nucleus —- shells

James Chadwick

Discovered the neutron

Order of discovery

electron, proton, neutron

Proton charge

+1

Proton mass

1

proton location

nucleus

neutron charge

0

neutron mass

1

neutron location

nucleus

electron charge

-1 (negative)

electron mass

1/2000

Electron location

shells

Overall charge of an atom

zero

Radius of an atom

1x10^-10m or 0.1nm

mass number (atomic mass)

The sum of protons and neutrons in the nucleus of an atom

Isotopes

Atoms of the same element that have different numbers of neutrons

atomic number

number of protons

How many neutrons in atom

Atomic mass - atomic number

Relative atomic mass

an average value that takes account of the abundance of the isotopes of the element

Relative atomic mass equation

Sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes

Maximum number of electrons within first shell

2

Maximum number of electrons within a shell ( after first )

8

electronic structure

a set of numbers to show the arrangement of electrons in their shells (or energy levels)

Each group has the same number of

valence electrons

Each period has the same number of what?

Shells

Mendeleev's periodic table

-arranged by atomic mass

-elements were great with other elements that has similar properties

-gaps were left for elements that weren't discovered

-mandela rearrange elements out of order from mass because of their property

Why did Mendeleev leave gaps in his periodic table?

leave room for elements that had not yet been discovered

Why did Mendeleev rearrange some elements

So they were grouped with other elements with similar properties

In periodic table elements are arranged

in order of increasing atomic number

Metals on the

left side of periodic table

Non-metals in the periodic table

right side

Properties of metals

-solid at room temp

-good conductors of heat and electricity because the delocalised electrons carry electrical current and heat

-malleable because the layers slide over each other easily

-shiny

- high ductility

- hard

- high density

- high melting points

properties of nonmetals

dull, brittle, poor conductors of electricity and heat , low melting point, , low density , low malleability and ductility

Group 1 name

alkali metals

Properties of group 1

Soft, low melting point, low density, most reactive , malleable , conducts electricity

Group 1 metal + water

metal hydroxide + hydrogen

Group 1 reaction with chlorine equation

Metal + chlorine —> metal chlorine

Group 1 reaction with oxygen

metal + oxygen -> metal oxide

Trends in Reactivity: Alkali metals

-Reactivity increases down the group

-Atoms get larger down the group: the outer electrons are further from the nucleus

-The nucleus has less attraction for the outer electron

-The outer electron is more easily lost

Observation of lithium in water

Fizzes , melts , moves on surface

lithium and water equation

2Li(s) + 2 H20 (l) —> 2 LiOH (aq) + H2 (g)

Sodium and water observations

Fizzes more , melts , moves on surface , may catch fire with yellow - orange flame

sodium and water equation

2Na(s) + 2H2O(l) -> 2NaOH(aq) + H2(g)

Potassium and water observations

Fizzes more , melts , moves on surface , may catch fire with purple flame

Potassium and water equation

2K + 2H2O -> 2KOH + H2

Lithium and chlorine observations

- burns and produces a white solid

Lithium and chlorine equation

2Li + Cl2 —-> 2LiCl

chlorine and sodium observation

Burns and produces a white solid

Equation sodium and chlorine

2Na+ Cl2 —> 2 NaCl

Observation chlorine and potassium

Burns and produces a white solid

Equation chlorine and potassium

2K + Cl2 —-> 2KCl

Observation oxygen and lithium

Burns with a red flame to give a white solid

Equation lithium and oxygen

4Li + O2 —> 2Li2O

observation of sodium with oxygen

burns with yellow/orange flame to

produces white solid

Equation of sodium with oxygen

4Na[s] + O2 [g] --> 2Na2O[s]

Observation potassium and oxygen

Burns with a lilac flame to give a white solid

Equation potassium and oxygen

4K+ 02 —-> 2K2O

Group 7 name

Halogens

Chlorine

Pale green gas

Bromine

Brown/ orange liquid

Iodine

Black solid

Trend in reactivity of the halogens

Reactivity decreases down the group. As we go down the group, the atoms get larger, so an incoming electron will be less tightly held by the attractive forces from the nucleus.

Group 7 melting and boiling points

increase as you go down the group

diatomic molecule

A molecule consisting of two atoms

Halide ions

the ions that are produced when atoms of chlorine and other halogens gain electrons

Chlorine react with

Less reactive halide solution ( bromide , iodide )

Chlorine solution with bromide halide solution

Changes from green to orange , product = potassium chloride

Chlorine and iodide halide solution

Changes from green to brown, product = potassium chloride

Bromine and iodide halide solution

Changes from yellow to brown , product = potassium bromide

noble gases

Have full outer shell which makes them very stable

Noble Gases Melting Points

increase down a group

transition metals

Form different ions which can have different charges

- form coloured compounds

- are useful as catalysts for many reactions

Difference between simple and fractional distillation

Simple distillation separates a liquid from a solid-liquid solution while fractional distillation separates a liquid from a solution of two or more liquids. Fractional distillation has a fractioning column which simple distillation doesn't have.

How to do fractional distillation

Different liquids have different boiling points when the mixture is heated

stationary phase

The phase that does not move in chromatography.

mobile phase of chromatography

The solvent that moves through the paper carrying different substances with it

Displacement reactions

When a more reactive metal displaces a less reactive metal from its compound.