C4 module

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Periodic table and atoms

Element = made of only one kind of atom

Elements are arranged in order of ascending proton number in the periodic table

Group = vertical column of elements, corresponds to the number of electrons in the shell of an atom

Period = horizontal row elements, corresponds to the number of shells in an atom

Nucleus = made up of protons and neutrons

Nucleus surrounded by electrons arranged in shells

Atoms has no overall charge

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Spectroscopy and Electron configuration

Line spectrum = light emitted from flame of an element when heated

Lithium = red flame

Sodium = yellow flame

Potassium = lilac flame

Electron configuration = how the electrons are arranged around nucleus

First shell = maximum of 2 electrons

Shells after this = maximum of 8 electrons

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Balanced Equations

Total mass of products = total mass of reactants

No atoms are lost or made in a chemical reaction

There are 4 steps to write a balanced equation...

- write word equation

- substitute in formulae

- balanced the equation by adding numbers in front of reactants/products

- write balanced symbol equation

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Alkali Metals

Alkali metals....

- group 1

- 1 electron in outer shell

The reactivity of alkali metals increases down the group

Alkali metals are more reactive down the group as the outer shell gets further from the nucleus and electrons are more easily lost.

Alkali metal + water = metal hydroxide + hydrogen

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Halogens are in group 7 and have 7 electrons in outer shell

The reactivity of halogens decreases down the group

At room temperature and room pressure....

- chlorine is a green gas

- bromine is an orange liquid

- iodine is a dark purple solid

Halogens are less reactive down the group as the outer shell gets further from the nucleus and electrons are less easily gained.

A more reactive halgen will displace a less reactive halogens from an aqueous solution of its salt.

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Ions = atoms that have gained or lost electrons so have an overall charge

Ionic bonding = transfer of electrons between metal atoms and non metals atoms

Atom loses electrons = positively charged ion

Atom gains electrons = negatively charged ion

Ionic compound = compounds of group 1 and group 7 elements. Form crystals as ions are arranged in regular lattice.

Ionic compounds = neutral substances = equal amounts of positive and negative charge.

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