C1 GCSE science

Flashcards for Chemistry Lecture Review

Element

Substances made of only one type of atom and found on the periodic table.

Compound

Substances made from two or more elements chemically bonded together with fixed ratios and different properties from their elements.

Mixture

Contain two or more substances (elements or compounds) not chemically bonded that can be separated physically.

John Dalton's Atomic Theory

Early 1800s, proposed that atoms are solid spheres.

J.J. Thomson's Atomic Model

1897: Discovered electrons; Plum pudding model (positive 'dough' with negative 'plums' = electrons).

Ernest Rutherford's Atomic Model

1909: Gold foil experiment; discovered the nuclear model (tiny, dense, positive nucleus with electrons around it); atoms are mostly empty space.

Niels Bohr's Atomic Model

Proposed that electrons orbit the nucleus in energy levels (shells).

James Chadwick's Discovery

1932: Discovered neutrons – neutral particles in the nucleus.

Proton

Charge = +1, Mass = 1

Neutron

Charge = 0, Mass = 1

Electron

Charge = –1, Mass = ~0 (very tiny)

Atomic Number

Number of protons = number of electrons (in a neutral atom)

Mass Number

Protons + neutrons

Isotopes

Atoms of the same element (same number of protons) with different numbers of neutrons → different mass numbers.

Electronic Structure

Arrangement of electrons in shells around the nucleus: 1st shell: max 2 electrons, 2nd shell: max 8 electrons, 3rd shell: max 8 electrons (for GCSE level).

Electronic Configuration

Shows how electrons are arranged (e.g., oxygen = 2,6).