Chemistry GCSE Review - States of Matter, Particles, Atoms, Elements, Compounds and Mixtures

Physical changes change a substance from one [blank_start]state of matter[blank_end] to another. This does not change the particles in the substance themselves, just their [blank_start]arrangement[blank_end] and level of energy. If a substance is [blank_start]solid[blank_end], heating it enough causes it to [blank_start]melt[blank_end], forming a liquid. Conversely, [blank_start]cooling[blank_end] a liquid enough causes it to freeze. From the [blank_start]liquid[blank_end] state, heating further causes evaporation and eventually [blank_start]boiling[blank_end], causing it to change into a [blank_start]gas[blank_end]. The process of [blank_start]condensation[blank_end] occurs when a gas is cooled enough for it to become a liquid. Some substances do not pass through the liquid state, and instead pass straight from solid to gas and back again. The passing from solid to gas after being heated is called [blank_start]sublimation[blank_end], with the passing back known as deposition.

Which of the following states of matter can be described as follows: 1) There is a weak force of attraction between molecules. 2) Its particles are in constant motion with random movement. 3) There is a definite volume

Gases have [blank_start]a very weak[blank_end] force of attraction between particles. These particles are free to move and are far apart. They have no definite shape or [blank_start]volume[blank_end], expanding to fill a container they are in. These particles move constantly [blank_start]in straight lines[blank_end], with random motion. The hotter the gas gets, the [blank_start]faster[blank_end] the particles move. Two things can happen to the gas when it is heated: either it expands, or the [blank_start]pressure[blank_end] increases.

Solids have a [blank_start]definite[blank_end] shape and volume and, although the particles do not move constantly, they vibrate about their positions. The [blank_start]hotter[blank_end] the solid becomes the more these particles vibrate (causing the solid to expand).

Diffusion is:

Label the structure of the atom.

The only sub-atomic particle without a charge is the [blank_start]neutron[blank_end].

What number explicitly tells you how many protons an atom has in its nucleus?

Molecules are held together by what kind of bonds?

Elements are substances that consist of [blank_start]only one[blank_end] type of atom. Many everyday substances are elements, including [blank_start]nitrogen[blank_end], oxygen, [blank_start]iron[blank_end], gold, [blank_start]copper[blank_end] and aluminium. If two atoms have the same number of [blank_start]protons[blank_end], they are of the same element. Compounds are comprised of [blank_start]two or more[blank_end] different elements chemically [blank_start]bonded[blank_end] in some way. There are three kinds of bonding, called [blank_start]covalent, ionic and metallic[blank_end]. Examples of chemical compounds include carbon dioxide ([blank_start]CO2[blank_end]), water ([blank_start]H2O[blank_end]), ethane ([blank_start]C2H6[blank_end]) and sulphuric acid ([blank_start]H2SO4[blank_end]). The constituent parts in a mixture, unlike in a compound, are [blank_start]not chemically bonded[blank_end]. These constituent parts also do not just have to be elements - they can also be compounds themselves. For example, air is a mixture of gases including carbon dioxide (CO2), oxygen ([blank_start]O2[blank_end]), nitrogen ([blank_start]N2[blank_end]), argon ([blank_start]Ar[blank_end]) and water vapour (H2O). Another example is crude oil, a mixture of different [blank_start]fractions[blank_end], which are themselves mixtures of various [blank_start]hydrocarbons[blank_end].