Sign In Request Beta Access
← Back to Chemistry

GCSE Chemistry 01 — Atomic Structure & the Periodic Table

Public

Topics include Atomic Structure & Subatomic Particles, Isotopes & Relative Atomic Mass, History of the Atomic Model, Electronic Configuration & Ion Formation, The Periodic Table: Structure & Trends, Group 1: The Alkali Metals, Group 7: The Halogens, and Group 0: The Noble Gases.

Chemistry EN
150 cards
Study this deck on Deckloop

Preview Cards

A sample of cards from this deck.

Example explainer

A sample of the AI explainer you can generate for cards in this deck.

Atomic Structure & Subatomic Particles

Atoms are the fundamental building blocks of matter, consisting of a central positive nucleus surrounded by negative electrons.

Key points

  • Nucleus: Contains protons and neutrons. It is very small (1/10,000th of the atom) but contains almost all the mass.
  • Electrons: Orbit in shells. They have negligible mass (approx 1/1836) and a charge of -1.
  • Atomic Number (Z): The number of protons. This defines the element.
  • Mass Number (A): The total number of protons + neutrons.
  • Neutrality: Atoms have no overall charge because the number of protons (+1) equals the number of electrons (-1).

Worked example

Question

An atom of Cobalt-59 is represented as 2759Co^{59}_{27}\text{Co}. Calculate the number of protons, neutrons, and electrons in this atom.

Solution

1. Protons: Look at the Atomic Number (bottom number). Protons = 27.
2. Electrons: In a neutral atom, electrons = protons. Electrons = 27.
3. Neutrons: Mass Number - Atomic Number. 59−27=3259 - 27 = 32 neutrons.

Common pitfalls

  • Confusing the Mass Number (top) with the Atomic Number (bottom).
  • Thinking the nucleus takes up a large part of the atom's volume (it is tiny; the atom is mostly empty space).
  • Stating that the mass number is the number of neutrons (it is protons + neutrons).

Prerequisites

  • Basic definition of matter
  • Simple subtraction skills
Further resources