ccea chem unit 1

Atom

The simplest part of an element that can exist and take part in chemical reactions.

Element

A pure substance which contains only one type of atom. It cannot be split into anything simpler by a chemical reaction.

Compound

A pure substance which contains two or more different elements chemically joined.

Mixture

A substance that contains two or more different elements not chemically joined and can be separated easily.

Atomic Number

The number of protons present in an atom.

Mass Number

The total number of protons and neutrons in an atom.

Isotopes

Atoms of the same element which have the same number of protons but a different number of neutrons.

Ion

A charged particle formed when an atom either loses or gains electrons.

Ionic Bond

The attraction between oppositely charged ions, forming large regular lattice structures.

Covalent Bond

The sharing of electron pairs between two or more non-metal atoms.

Metallic Bond

The attraction between positive metal ions in a regular lattice and delocalised electrons.

Lone Pair of Electrons

Two electrons that are unbounded in a molecule.

Molecule

Two or more atoms covalently bonded together.

Diatomic

Two atoms covalently bonded in a molecule.

Alloy

A mixture of two or more elements, at least one of which is a metal, and the resulting mixture has metallic properties.

Malleable

Can be hammered into shape.

Ductile

Can be drawn into a wire.

Sonorous

Can produce a ringing sound.

Lustrous

Shiny when freshly cut.

Allotropes

Different forms of the same element in the same physical state.

Precipitate

A solid which forms when two solutions mix.

Reliability

Whether or not the same result could be obtained if the experiment was repeated.

Validity

Whether or not the test fulfils the purpose of which it was carried out.

Ionic Equation

The equation to show the reaction between a positive ion and a negative ion to form a compound. Spectator ions are cancelled.

Indicator

A chemical which is one colour in an acid and a different colour in an alkali.

Acid

A substance which dissolves in water to produce hydrogen ions.
H+(aq)

Strong Acid

An acid which is completely ionised in water.

Weak Acid

An acid which is only partially ionised in water.

Alkali

A soluble base which dissolves in water to produce hydroxide ions.

Strong Alkali

An alkali which is completely ionised in water.

Weak Alkali

An alkali which is only partially ionised in water.

Base

A metal oxide or metal hydroxide. OH-(aq)

Neutralisation

The reaction between the hydrogen ions of an acid and the hydroxide ions of an alkali to produce water. H+(aq) + OH-(aq) --\> H2O(l)

Exothermic Reaction

A chemical reaction that releases heat.

Endothermic Reaction

A chemical reaction that takes in heat.

Salt

A compound formed when some or all of the hydrogen ions in an acid are replaced by metal ions.

Molecular Ion

A charged particle containing more than one element.

Solvent

The liquid in which the solute dissolves.

Solute

The solid which dissolves in a solvent.

Solution

The mixture formed when a solute dissolves in a solvent.

Soluble

A substance which dissolves in a solvent.

Insoluble

A substance which does not dissolve in a solvent.

Anhydrous

A solid which does not contain water of crystallisation and is powdery.

Hydrated

A solid which contains water of crystallisation and is crystalline.

Dehydration

The removal of water of crystallisation from a compound.

Solubility

The mass of solute in grads needed to saturate 100 grams of water at a particular temperature.

Saturated Solution

One in which the maximum amount of solute possible has dissolved in the solvent at a particular temperature.

Residue

The solid remaining in the filter paper during filtration.

Filtrate

The liquid that passes through the filter paper during filtration.

Distillate

The liquid collected during distillation.

Miscible

Two liquids that mix together.

Imiscible

Two liquids that do not mix together.

Group

A vertical column in the periodic table.

Period

A horizontal row in the periodic table.

Melting Point

The temperature at which a solid is changed to a liquid on heating.

Boiling Point

The temperature at which a liquid is changed to a gas on heating.

Evaporation

The change from liquid to gas on heating.

Condensation

The change from gas to liquid on cooling.

Melting

The change from solid to liquid on heating.

Freezing

The change from liquid to solid on cooling.

Sublimation

The direct change from solid to gas, on heating, without passing through the liquid state.

Displacement Reaction

One in which the more reactive element will displace the less reactive element from a solution of its compounds.

ionic bonding (non-metal/metal) physical properties

large lattice structure;
-form crystalline solids
-high melting point
-hard
-conducts electricity in the liquid state

covalent bonding (non-metals)

-low melting point
-most are insoluble in water
-doesn't conduct electricity

giant covalent bonding- diamond

very strong giant covalent bonds;
-hard
-high melting point
-insoluble in water

giant covalent bonding- graphite

very strong giant covalent bonds;
-(atoms are in layers) lubricant + pencils
-soft
high melting point
only non-metal that can conduct electricity

giant covalent bonding- graphene

a single layer, one atom thick of graphite arranged in a honey-comb structure;
-ultra-light
-can conduct electricity
-flexible
-transparent

metals can conduct electrity

-in metal atoms, the outer electrons are free to move \= they are delocalised, this is why metals, even when in the liquid state, can conduct electricity

bonding in metals

-very strong, due to the attraction between the positive ions, which are in a regular lattice and the delocalised ions

Group 1 - alkali metals

-very reactive in water
-soft
-shiny when cut
-tarnishes in the air
-low density
stored in oil

Group 2 - alkaline earth metals

-less reactive than group 1
-hard

Group 7 - halogens

-toxic
-coloured

Group 0 (8)

-inert
-colorless
-glow when electricity passes through them

test for chlorine (green gas)

-using damp universal indicator paper
-will turn red (acidic properties)
-bleach it white

sublimation (goes form the solid to the the gas state without becoming liquid) of iodne

-heat the iodine and it will turn to gas
-the evaporating dish is filled with ice, to cool the gas and allow the solid iodine to form
I2(s)-\>I2(g)

when halogens react...

they will gain one electron to obtain a full outer shell, an anion is formed \= explained using half equation

half-equation; -flourine, - iodine, -bromine, -chlorine

F+e\- -\> F- \= pale yellow
I+e\- -\> I- \= grey solid, purple gas
Br+e\- -\> Br- \= red brown
Cl+e\- -\>Cl- \= pale green

-copper (ii) oxide
-copper (ii) carbonate
-hydrated copper (ii) sulfate
-anhydrous copper (ii) sulfate

-black
-green
-blue
-white

-Hydrochloric acid (weakest)
-Sulfuric acid (strongest)
-Nitric acid (mid-strength)

-HCl
-H2SO4
-HNO3

when metal react in acid, a salt and hydrogen are formed, this isn't a neutralisation reaction as water isn't formed;

2H2 + O2 --\> 2H2O
Hydrogen + oxygen --\> water

in the reaction of metals in acid, salts are formed

salt is formed because the hydrogen ions ions in the acid are replaced by the metal ions. This is a displacement reaction.

metal ions

lithium - crimson
sodium - orange/yellow
potassium - lilac
calcium - brick red
copper green/blue