Science: Year 10 AT1

Revision

Types of Bonds

Ions

Atoms that have lost or gained electrons; a positive ion is a cation, and a negative ion is an anion.

These are represented by drawing the nucleus and electron shells, enclosed by brackets with the ion’s charge.

Ionic

Created with cations and anions, ionic compounds are formed through the electrostatic attraction between these oppositely charged particles, resulting in a stable structure.

Covalent

When 2 non-metal atoms share valence electrons, covalent bonds are formed.

These are represented with a dot and cross diagram.

Atoms and The Periodic Table

Hydrogen’s presence is measured with the pop test.

The flame test and the limewater test measures CO2 presence.

The ember test measures Oxygen presence

Chemical Reactions

Law of Conservation of Mass

In every chemical equation, mass must be conserved, meaning the mass is equivalent for the reactants and the products in a chemical equation.

Masses may be influenced by the outside atmosphere - if reactants are gas the products may increase and if a product is gas the mass may decrease. (because the gas is released into the atmosphere unless performed in a chamber)

Equations

1. Identify the elements

2. Look at the valency to determine the charge of a transition metal where present

3. Balance the equation - ensuring mass is conserved.

Word Equation

1. Name compounds correctly

2. Write all reactants and products in word form only.

Naming Covalent compounds

1. The first element keeps its name

2. The second element changes to “-ide”

3. We use prefixes according to the number of atoms; but if the first one has one we don’t keep mono

List of prefixes

Naming Ionic Compounds

1. Name the metal element

2. Non-metal named second

   add “ide” at the end

3. If metal has more than one charge, you use Roman Numerals to indicate the charge

   eg. Iron (II) or Iron (I)

Acid/Bases

This is a neutralisation reaction, meaning when acids and bases have an equal number of hydrogen and hydroxide atoms they form water (a neutral solution) and a salt. In this reaction, salt is the solute and water is the solvent.

Acid + Base → Salt + Water

Acid/Carbonate

When acid is added to a different base, carbonate, it follows this form:

Acid + Carbonate → Salt + Carbon Dioxide + Water

Acid/Metal

Acids + Metals → Salt + Hydrogen

Solubility

When a substance is soluble:

• It dissolves in water (solvent)

• No precipitate forms

When a substance is insoluble:

• It does not dissolve in water (solvent)

• It forms a precipitate

Precipitation Reactions

The standard form of a precipitation reaction is:

AB + CD → AD + BC

Also known as double displacement.

If one of these products is in a solid form, a precipitate forms.

When writing precipitate reactions, we must indicate the state of the reactants and products:

Lead (II) Nitrate (aq) + Potassium iodide (aq) → Lead (II) Iodide (s) + Potassium Nitrate (aq)

pH

Acids

• Proton donor (H+)

• Sour taste

• React with metals (reactive)

• Can destroy or damage other substances (corrosive)

• When dissolved in water, it is called a solution.

Bases

• Proton acceptor (OH-)

• Can be solid or liquid

• Solid bases dissolve in water (alkali)

• Soapy, slippery feel

• Bitter taste

• Corrosive, can also burn skin (caustic)

Neutral substances

• Formed by mixing acid and a base

• Not corrosive

• Taste is sweet, salty, or none

Acidity

The acidity of a solution is a measure of its Hydrogen concentration

• The higher the H+ concentration, the more acidic.

• The lower the H+ concentration, the more basic.

The extremes of this scale are usually more dangerous

• pH 1-2 = strong acid

• pH 3-6 = weak acid

• pH 7 = neutral

• pH 8-11 = weak base

• pH 12-14 = strong base

Indicators

Universal indicator

An indicator is a substance that changes colour in the presence of acidic, basic, or neutral solutions.

The universal indicator measures the full spectrum.

You place in a few drops, and the solution will change colour, matching the universal pH scale; this will allow you to classify if the substance is acidic, basic or neutral.

Litmus paper

Litmus paper classifies whether a substance is acidic, basic, or neutral.

• Acid = red

• Base = blue

• No colour change = neutral

Red paper can either stay red or turn blue, and blue paper can either stay blue or turn red.

Risk assessment

A risk assessment is when you identify the potential hazards of a scientific experiment and decide how to reduce the risk of harm. You’ll list:

• The hazards (things that could cause harm).

• The risks (how the hazard could cause harm).

• The safety measures (things you’ll do to minimize the risk).

For example, in a lab with acids, the hazard is the acid itself (it’s corrosive), the risk is potentially getting it on your skin, and the safety measures include wearing gloves, goggles, and a lab coat.

Safety Data Sheets

A Safety Data Sheet is a document that provides information about the properties of a chemical substance. It includes:

• Hazards of the chemical.

• Precautionary measures (how to safely handle, store, and dispose of the chemical).

• First-aid measures in case of exposure or accident.

These sheets are essential for ensuring everyone in the lab is informed about the chemicals used and how to work with them safely.

Since you're likely working with acids in the experiment, think about common risks like:

• Corrosiveness (to skin, eyes, or other materials)

• Inhalation hazards (fumes from acids)

• Spills and splashes

For your risk assessment, you’d include safety measures like wearing goggles, gloves, and a lab coat, and knowing what to do in case of an accident (like flushing with water or using a neutralizing solution). This will be key for your experiment.