Materials, Atomic Structure and Bonding
Particles and states
You must understand the particle model: solids, liquids and gases differ in arrangement and movement of particles. Changes of state involve energy but not a change in substance. Diffusion results from random particle motion, and its rate rises with temperature. A trap is saying particles expand when a substance is heated; the particles move faster and spread further apart, but they do not grow.
Atomic structure
Know protons, neutrons and electrons, their charges and positions, and how to use atomic number and mass number. Isotopes have the same protons but different neutrons. Electrons occupy shells, with the first shell holding two and the next holding eight.
The periodic table
Elements are arranged by increasing atomic number. Groups have similar properties; group number relates to outer electrons. Metals are on the left, non-metals on the right.
Bonding
Ionic bonding involves transfer of electrons and gives high melting points; covalent bonding involves sharing electrons and often gives low melting points; metallic bonding involves a lattice of positive ions in a sea of electrons, explaining conduction. A trap is confusing the type of bonding with the state of the substance at room temperature.
Worked example
An atom has 11 protons, 12 neutrons and 11 electrons. Its mass number is 11 + 12 = 23, its atomic number is 11, and its electron arrangement is 2, 8, 1, so it is a group 1 metal that loses one electron to form a 1+ ion.