Chemistry

Elements, compounds and mixtures An element contains only one type of atom. A compound contains atoms of two or more elements chemically bonded in fixed proportions. A mixture contains two or more substances that are not chemically bonded. Its components can be separated by physical methods. Atomic structure Particle Relative charge Relative mass Location Proton $+1$ $1$ Nucleus Neutron $0$ $1$ Nucleus Electron $-1$ $\frac{1}{1840}$ Shells around nucleus The proton number, or atomic number, is the number of protons. The mass number, or nucleon number, is the total number of protons and neutrons. In a neutral atom, number of electrons equals number of protons. ...

Solids, liquids and gases State Arrangement and separation Motion Macroscopic properties Solid Particles closely packed in a regular arrangement Vibrate about fixed positions Fixed shape and volume; almost incompressible Liquid Particles close together in an irregular arrangement Move and slide past one another Fixed volume; takes container shape; almost incompressible Gas Particles far apart in a random arrangement Move rapidly and randomly in all directions No fixed shape or volume; easily compressed; low density These descriptions apply to particles, not necessarily individual atoms. A particle may be an atom, molecule, or ion. ...

Marking Scheme: Metals This is the marking scheme for quiz: C9 - Metals Quiz Topic Guide: C9 - Metals Section 1: Core Syllabus Question 1 Good conductor of heat [1] Good conductor of electricity [1] Malleable / Ductile / High melting point / Lustrous (Any one) [1] Question 2 A list of metals [1] Arranged in order of their reactivity/decreasing reactivity [1] Question 3 (a) Bright white light / intense white flame [1] (b) $2Mg(s) + O_2(g) \rightarrow 2MgO(s)$ [2] (1 for correct formula, 1 for balancing) ...

Chemistry Quiz: Metals Question 1 List three general physical properties of metals. [3] Question 2 Define the term ‘reactivity series’. [2] Question 3 When magnesium is heated in air, it reacts with oxygen. State the observation during this reaction. [1] Write a balanced symbol equation for this reaction. [2] Question 4 Explain why aluminum is extracted by electrolysis rather than by reduction with carbon. [2] Question 5 Steel is an alloy of iron and carbon. Explain why steel is harder than pure iron. [2] ...