A level biology

• What is an orbital? A region of space around the nucleus of an atom which can contain up to two electrons with opposite spins.
• List the types of subshells in order, with their total number of orbitals. s (1), p (3), d (5), f(7)
• How do you work out relative atomic mass? Σ(Abundance x mass)/total abundance
• What are isotopes? Atoms of the same element (same number of protons) with different masses (different numbers of neutrons)
• What technique can be used to find atomic masses? Mass Spectrometry
• What is a nuclear fusion reaction? Two light atomic nuclei fuse together to form a single heavier nucleus of a new element, releasing lots of energy.
• What does an atomic emission spectrum look like? A black box with coloured lines
• What does an atomic absorption spectrum look like? A rainbow box with black lines
• Why are there discrete lines on the absorption and emission spectra? Energy of electrons is quantised and when given the right amount of energy, they can jump up energy levels. They release this when they go back down. The exact amount of energy needed for a particular change is proportional to the frequency at which they absorb or emit.
• What is a light particle called? Photon
• How many electrons can fit in a main energy level, n? 2n2
• If you know the wavelength of an emitted wave, what two equations do you need to work out the energy of it? c=λν, E = hνc = speed of light, h = Planck's constant (both on data sheet). λ= wavelength (m), ν = frequency (Hz), E = energy (J)
• What are groups? Vertical columns on the periodic table
• What are periods? Horizontal rows on the periodic table
• What charge do group 1 elements form? 1+
• What charge do group 2 elements form? 2+
• What charge do group 3 elements form? 3+
• What charge do transition metals form? Varies, but positive
• In the NAME of a transition metal compound, how do you know the metal's charge? It will be in brackets, in roman numerals.
• What charge do group 5 elements form? 3-
• What charge do group 6 elements form? 2-
• What charge do group 7 elements form? 1-
• What is a dative covalent bond? A covalent bond in which both electrons are donated by the same species.
• What shape and bond angle: 2 bonding regions, 0 lone pairs. linear, 180˚
• What shape and bond angle: 3 bonding regions, 0 lone pairs Trigonal planar, 120˚
• What shape and bond angle: 4 bonding regions, 0 lone pairs Tetrahedral, 109.5˚
• What shape and bond angle: 2 bonding regions, 2 lone pairs V-shaped/bent/non-linear. 104.5˚
• What shape and bond angle: 3 bonding regions, 1 lone pair Pyramidal, 107˚
• What shape and bond angle: 6 bonding regions, 0 lone pairs Octahedral, 90˚
• Why do molecules form the shapes they do? Electron pairs (bonds or lone pairs) around the central atom repel one another so they spread out as far in 3D space as possible. Lone pairs repel more than bonding pairs.
• How do you calculate moles from mass? Moles = mass/molar mass
• What number represents how many particles in a mole? Avogadro's number
• What are the units of molar mass? g mol -1
• How do you calculate relative formula mass? Add up all the masses of all the atoms in the formula
• What is the empirical formula? The simplest whole number ratio of atoms in a compound (or element). (We always use the empirical formula for describing the formula of giant lattices, but usually not for simple molecular substances.)
• What is water of crystallisation? Molecules of water found in the crystals of some ionic lattices.
• How can we determine how much water of crystallisation a compound has? Weigh it. Heat it to constant mass. Weigh again. The difference in mass is grams of water. The end mass is grams of compound. Determine moles of each and turn it into a ratio.
• What is the formula of a sulfate ion? SO42-
• What is the formula of the hydroxide ion? OH-
• What is the formula of the nitrate ion? NO3-