Science: Year 10 AT1

Ion

An ion is an atom that has lost or gained electrons. A positive ion is a cation, and a negative ion is an anion.

Ions representation

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

Ionic bonds formation

Ionic bonds are formed through the electrostatic attraction between cations and anions, resulting in a stable compound.

Covalent bond

A covalent bond is formed when two non-metal atoms share valence electrons. Represented with a dot and cross diagram.

Law of Conservation of Mass

In every chemical equation, mass must be conserved, meaning the mass of the reactants equals the mass of the products.

Influence on conservation of mass

The outside atmosphere can affect mass conservation, as gases can escape or enter the atmosphere.

Balancing chemical equations process

Identify the elements, determine the charges (especially of transition metals), and balance the equation.

Neutralisation reaction

Acid + Base → Water + Salt; is a type of double displacement reaction.

General equation for acid + metal

Acids + Metals → Salt + Hydrogen.

Precipitation reaction

A precipitation reaction occurs when two aqueous solutions react to form a solid precipitate.

States in writing precipitation reactions

Indicate whether reactants and products are solid (s), liquid (l), gas (g), or aqueous (aq).

pH

pH measures the concentration of hydrogen ions (H+) in a solution.

Properties of acids

Proton donors (H⁺), have a Sour taste, can Corrosive, Dissolve in water to form acidic solutions

Properties of bases

Proton acceptors (OH⁻), have a Bitter taste and Slippery feel, Dissolve in water to form basic solutions, and can be corrosive or caustic.

Properties of neutral substances

Neutral substances are formed by mixing an acid and a base; they are not corrosive.

Indicators purpose

Indicators change color to show whether a solution is acidic, neutral, or basic.

Universal Indicator role

Universal Indicator shows a full range of pH values by changing color.

Litmus paper use

Litmus paper classifies whether a substance is acidic (red), basic (blue), or neutral (no change).

Difference between Litmus paper and Universal Indicator

Litmus paper indicates acidity or basicity; Universal Indicator shows the full pH range.

Risk assessment purpose

A risk assessment identifies hazards in an experiment and sets safety measures to minimize harm.

Safety Data Sheet

A Safety Data Sheet provides information on hazards, handling, and first-aid measures for a chemical.

Acid + carbonate reaction

Acid + Carbonate → Salt + Carbon Dioxide + Water.

Safety measures for working with acids

Wear goggles, gloves, and a lab coat; be prepared for spills and follow first-aid procedures.

What is the difference between strong and weak acids/bases in terms of dissociation?

• Strong Acids/Bases: Fully dissociate in water (one-way arrow). High concentration of ion (H/OH)

• Weak Acids/Bases: Partially dissociate, meaning some undissociated molecules are still present. (reversible arrow). Low concentration of ion (OH)

Acids and bases (in water)

Acids and bases are chemicals that are effective proton donors (H⁺) or acceptors (OH⁻) when dissolved in water. In their pure form, they may not show acidic or basic properties until they dissolve in water to dissociate into their respective ions.

Define an aqueous solution

A mixture where a substance is dissolved in water.

Endothermic reaction

A chemical reaction that absorbs energy, usually in the form of heat, causing the temperature of the surroundings to drop.

Exothermic reaction

A chemical reaction that releases energy, usually in the form of heat, causing the temperature of the surroundings to rise.

How to test for oxygen

Blow out a match, and place it in a test tube with oxygen, if it relights, oxygen is present.

Naming covalent compounds

We use prefixes to identify the amount of each atom; but if the first has only one we remove the prefix

Prefixes

di 2 tri 3 tetra 4 penta 5 hexa 6 hepta 7