Page 2: Chemical Equations and Conservation of Mass

This page focuses on understanding chemical equations and reactions, a key topic in C1 chemistry. It explains how to write and balance chemical equations, and introduces the concept of conservation of mass.

Chemical equations are described as representations of reactions, showing reactants and products. The page emphasizes that in chemical reactions, atoms are rearranged rather than created or destroyed.

Example: The formation of water is shown as a chemical equation: H₂ + O₂ → H₂O

The importance of using symbol equations is highlighted, as they help visualize the quantities of substances involved in a reaction.

Highlight: Balanced equations are crucial because they reflect the law of conservation of mass.

The page explains that the number of each type of atom must be the same on both sides of the equation for it to be balanced. This principle is linked to the conservation of mass, stating that the total mass of the products equals the total mass of the reactants in a chemical reaction.

Vocabulary: State symbols are introduced to provide additional information in chemical equations:

• $s$ for solid
• $l$ for liquid
• $g$ for gas
• (aq) for aqueous (dissolved in water)

An example of a balanced equation with state symbols is provided:

Example: CaCO₃$s$ → CaO$s$ + CO₂$g$

This page is essential for students preparing for GCSE Chemistry balancing equations and understanding the principles of chemical reactions. It provides a solid foundation for more advanced topics in chemistry and is valuable for both BBC Bitesize GCSE revision and classroom learning.

Page 1: Atomic Structure and the Periodic Table

This page covers the fundamental concepts of atoms, elements, compounds, and mixtures, as well as the structure of atoms and the organization of the periodic table.

Definition: An atom is the smallest part of an element that can exist.

The page explains that all substances are made of tiny particles called atoms. It distinguishes between elements, compounds, and mixtures:

• Elements consist of only the same type of atoms
• Compounds are made up of two or more different types of substances chemically bonded together
• Mixtures contain two or more different types of substances that aren't chemically bonded and can be separated physically

Highlight: The atomic structure is detailed, showing protons and neutrons in the nucleus, with electrons orbiting in shells.

A table is provided showing the relative charge and mass of protons, neutrons, and electrons:

Example:

• Proton: Charge +1, Mass 1
• Neutron: Charge 0, Mass 1
• Electron: Charge -1, Mass 1/1800

The periodic table's organization is explained:

• Separated by a staircase to distinguish metals from non-metals
• Vertical columns are called groups $0-7$
• Horizontal rows are called periods $1-7$

Vocabulary: Atomic number refers to the number of protons in an atom, while atomic mass is the total number of protons and neutrons.

The page concludes with information on electron configurations and how elements in different groups gain or lose electrons:

• Group 1 loses 1 electron
• Group 2 loses 2 electrons
• Group 3 loses 3 electrons
• Group 5 gains 3 electrons
• Group 6 gains 2 electrons
• Group 7 gains 1 electron

This information is crucial for GCSE Chemistry C1 revision and understanding the periodic table groups and periods.