Structure 1.1—Introduction to the particulate nature of matter (SL/HL)

Structure 1.1.1 Elements are the primary constituents of matter, which cannot be chemically broken down into simpler substances.

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—The temperature, T , in Kelvin (K) is a measure of average kinetic energy Ek of particles.

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Structure 1.2—The nuclear atom

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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1.3—Electron configurations

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 of2n^2 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.

Structure 1.3.6—In an emission spectrum, the limit of convergence at higher frequency corresponds to ionization. AHL

Structure 1.3.7—Successive ionization energy (IE) data for an element give information about its electron configuration. AHL

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Structure 1.4—Counting particles by mass: The mole.

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 has the units g mol–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—Ideal gases

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 specific 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 and the combined gas law

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