Topic 1
Structure 1.1.1 — Elements are the primary constituents of matter, which cannot be chemically broken down into simpler substances. Compounds consist of atoms of different elements chemically bonded together in a fixed ratio.
Mixtures contain more than one element or compound in no fixed ratio, which are not chemically bonded and so can be separated by physical methods.
Structure 1.1.2 — The kinetic molecular theory is a model to explain physical properties of matter (solids, liquids, and gases) and changes of state.
Structure 1.1.3 — Temperature (in K) is a measure of the average kinetic energy (Ek) of particles.
Structure 1.2.1 — Atoms contain a positively charged, dense nucleus composed of protons and neutrons (nucleons). Negatively charged electrons occupy the space outside the nucleus
Structure 1.2.2 — Isotopes are atoms of the same element with different numbers of neutrons.
Structure 1.2.3 — Mass spectra are used to determine the relative atomic masses of elements from their isotopic composition.
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Structure 1.3.1 — Emission spectra are produced by atoms emitting photons when electrons in excited states return to lower energy levels.
Structure 1.3.2 — The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at
higher energies.
Structure 1.3.3 — The main energy level is given an integer number, n, and can hold a maximum of 2n2 electrons.
Structure 1.3.4 — A more detailed model of the atom describes the division of the main energy level into s, p, d and f sublevels of successively higher energies.
Structure 1.3.5 — Each orbital has a defined energy state for a given electron configuration and chemical environment, and can hold two electrons of opposite spin. Sub levels contain a fixed number of orbitals, regions
of space where there is a high probability of finding an electron.
Structure 1.3.6 — In an emission spectrum, the limit of convergence at higher frequency corresponds to ionization.
Structure 1.3.7 — Successive ionization energy data for an element give information about its electron configuration.
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Structure 1.4.1 — The mole (mol) is the SI unit of amount of substance. One mole contains exactly the number of elementary entities given by the Avogadro constant.
Structure 1.4.2 — Masses of atoms are compared on a scale relative to
12C and are expressed as relative atomic mass (Ar) and relative formula mass (Mr).
Structure 1.4.3 — Molar mass(M) hasthe units gmol–1
Structure 1.4.4 — The empirical formula of a compound gives the simplest ratio of atoms of each element present in that compound. The molecular formula gives the actual number of atoms of each element present in a molecule.
Structure 1.4.5 — The molar concentration is determined by the amount of solute and the volume of solution.
Structure 1.4.6 — Avogadro’s law states that equal volumes of all gases measured under the same conditions of temperature and pressure contain equal numbers of molecules.
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Structure 1.5.1 — An ideal gas consists of moving particles with negligible volume and no intermolecular forces. All collisions between particles are considered elastic.
Structure 1.5.2 — Real gases deviate from the ideal gas model, particularly at low temperature and high pressure.
Structure 1.5.3 — The molar volume of an ideal gas is a constant at a specic temperature and pressure.
Structure 1.5.4 — The relationship between the pressure, volume, temperature and amount of an ideal gas is shown in the ideal gas equation pV = nRT
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