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| Questão | Responda |
| Isotope | Atoms of the same element, with the same number of protons but a different number of neutrons |
| Relative atomic mass | The average mass of the naturally occurring isotopes of the element relative the mass of an atom of carbon-12, which has a mass of 12 |
| Relative isotopic mass | The average mass of a naturally occurring isotope of the element relative to the mass of an atom of carbon-12, which has a mass of 12 |
| Avogadro's Constant | The number of particles per mole (6.02*10^23 mol^-1) |
| Mole | The mole is defined as the amount of substance which contains as many elementary particles as there are atoms in 12g of carbon-12 |
| Molar mass | The molar mass is the mass (in g) of one mole of substance. It has units of gmol-1 |
| Empirical formula | The simplest whole number ratio of atoms of each element present in a compound |
| Molecular formula | The actual number of atoms of each element in a molecule |
| Concentration | The amount of solute (in mol) per 1dm^3 of solution, has the units moles per dm^3 (mol dm^-3). |
| Acids | Proton donors. When they’re in water they release H+ ions into the solution. |
| Bases | Proton acceptors, they take H+ ions and neutralise acids. |
| Alkali | Soluble base which releases OH- ions in solution. |
| Salt | Produced when a H+ ion is replaced by a metal ion or NH4 +. |
| Anhydrous | Substance containing no water molecules. |
| Hydrated | Crystalline compound containing water molecules. |
| Water of Crystallisation | Water molecules which form part of the crystalline structure of a (hydrated) compound. |
| Oxidation | Loss of electrons (OIL, oxidation is loss), increase in oxidation number shows that a species has been oxidised. |
| Reduction | Gain of electrons (RIG, reduction is gain), decrease in oxidation number shows that a species has been reduced. |
| Redox reaction | A reaction in which species are both reduced and oxidised. |
| Disproportionation reaction | A reaction in which the same species is both reduced and oxidised. |
| First Ionisation energy | The energy required to remove one electron from each atom in one mole of gaseous atoms to make one mole of gaseous unipositive ions |
| Second Ionisation energy | The energy required to remove one electron from each unipositive ion in one mole of gaseous unipositive ions to make one mole of gaseous dipositive ions |
| Nuclear charge | The attraction from the protons in the nucleus with electrons. Protons have a positive charge and electrons have a negative charge, the greater the number of protons (The atomic number of the element), the greater the nuclear charge. Increases along a period. A higher nuclear charge makes it more difficult to remove an electron from the atom’s outer shell, causing the ionisation energy to increase. |
| Electron shielding | The number of shells of electrons between the nucleus and the outer shell of electrons. Increases down a group. Electrons repel each other so the more electrons repelling the electrons in the outer shell, the easier it’ll be to remove them, causing the ionisation energy to decrease. |
| Atomic radius | The distance from the outer shell of electrons to the nucleus of the atom. Increases down a group. A greater atomic radius means the outer shell electrons are under less influence from the attraction from the nucleus, this makes it easier to remove the electrons, causing the ionisation energy to decrease. |
| Orbital | A region that can hold up to two electrons of opposite spins (Up and down). Orbitals in an s-subshell are spherical, orbitals in a p-subshell are hourglass shaped. |
| Subshell | The space an electron can occupy within each shell. An s-subshell has one orbital (And so can hold a total of 2 electrons), a p-subshell has 3 orbitals (6 electrons), a d-subshell has 5 orbitals (10 electrons), and an f-subshell has 7 orbitals (14 electrons). |
| Ionic bonding | Electrostatic attraction between oppositely charged ions. |
| Covalent bonding | The electrostatic attraction between a positively charged nucleus and a shared pair of electrons. |
| Dative covalent bonding | A bond formed when one of the bonding atoms gives both of a pair of electrons. |
| Intermolecular forces | The forces of attraction between molecules. The strength or amount of intermolecular forces are what affect the substance's melting/boiling points - Stronger intermolecular forces require more (heat) energy to break. |
| Electronegativity | The power of attraction between a bonded atom and a pair of electrons in a covalent bond. |
| Dipole-dipole interactions | An intermolecular force. Molecules with permanent dipoles allow for weak intermolecular bonds to be formed between the molecules. |
| Van der Waal forces | Van der Waals forces are another type of intermolecular force. Van der Waals are formed when the movement of electrons unbalances the distribution of the charge in the shells, this causes an instantaneous dipole to form - This in turn attracts/repels electrons in neighbouring molecules which allows them to form instantaneous dipoles. Van der Waals forces increase as the number of electrons in the molecules increases and as the surface contact of the molecules increases. |
| Hydrogen bonding | The interaction between the lone pair of electrons on a nitrogen, oxygen or fluorine atom and a hydrogen atom which is bonded to an N, O or F atom |
| Metallic bonding | The attraction of positive metal ions to delocalised electrons. |
| Giant ionic lattice | Formed by the attraction of oppositely charged ions, each ion is surrounded by the oppositely charged ions and the ions attract each other to form a giant lattice. |
| Giant covalent lattice | Three dimensional structure of atoms bonded together by strong intramolecular covalent bonds. |
| Giant metallic lattice | Lattices which contain ionised atoms in fixed positions with delocalised outer shell electrons which spread, and can freely move, throughout the structure. |
| Simple molecular lattice | Three dimensional structure of molecules bonded together by weak intermolecular forces, such as Van der Waals forces |
| Periodicity | A repeating pattern of properties of elements across different periods in the Periodic table. |
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