Year 9 Science: Atoms, lons, and Chemical Reactions

Vocabulary flashcards covering the fundamentals of atomic structure, periodic table organization, electron configuration, ionic bonding, chemical reactions, and acid-base chemistry based on the lecture notes.

Element

A substance that consists of only one type of atom.

Atom

The smallest particle of an element that can exist, containing protons, neutrons, and electrons.

Atomic number

Represents the number of protons in the nucleus of an atom.

Mass number

The total number of protons and neutrons in the nucleus of an atom ($\text{Mass number} = \text{protons} + \text{neutrons}$).

Periods

The 7 horizontal rows on the periodic table.

Groups

The vertical columns on the periodic table; elements in the same group often share characteristics, such as valence electrons.

Electrons

The negatively charged subatomic particles found in shells surrounding the nucleus.

Electron configuration

The arrangement of electrons in the shells around the nucleus of an atom.

The 2, 8, 8, 2 rule

The pattern of how many electrons can fit in each shell for the first 20 elements, filling from the shell closest to the nucleus first.

Valence electrons

The electrons located in the outer shell of an atom.

Cations

Positively charged ions formed when atoms (typically metals) lose electrons.

Anions

Negatively charged ions formed when atoms (typically non-metals) gain electrons.

Ionic bond

The attraction between the opposite charges of cations and anions, also known as electrostatic attraction.

Lattice structure

A strong structure formed through multiple ionic bonds, resulting in high boiling and melting points.

Polyatomic ion

A charged ion composed of two or more atoms bonded together, such as Sulfate ($SO_4^{2-}$) or Phosphate ($PO_4^{3-}$).

Physical Change

A change of state, size, or shape where no new substance is made and the chemical composition remains the same.

Chemical Change

A change in chemical composition that results in the formation of a new substance through the breaking or forming of chemical bonds.

Reactants

Substances that go into a chemical reaction, located on the left-hand side of a chemical equation.

Products

New substances formed in a chemical reaction, located on the right-hand side of a chemical equation.

Law of conservation of mass

States that mass is neither created nor destroyed in a chemical reaction; the mass of products must equal the mass of reactants.

Acid

A substance that donates hydrogen ions ($H^+$), typically tastes sour, and can be corrosive.

Base

A substance that accepts hydrogen ions ($H^+$), tastes bitter, and feels slippery or soapy to the touch.

Alkali

A base that is soluble in water.

pH

Defined as 'the potential of hydrogen,' it is a logarithmic scale from 0 (very acidic) to 14 (very basic) measuring the concentration of hydrogen ions ($H^+$).

Acid-base indicators

Substances that change colour depending on the pH of a solution due to changes in their chemical structure.

Neutralisation

The reaction between an acid and a base which 'cancel each other out' to produce water, a salt, and sometimes a gas.

Acid rain

Rain formed when water reacts with gases such as carbon dioxide, sulfur dioxide, and nitrogen oxide produced by burning fossil fuels.