| List some ways to increase the rate of reaction | Increasing temperature, increasing concentration of a reactant, increasing surface area/decreasing particle size, through the use o a catalyst. |
| What is a catalyst? | A substance that speeds up a chemical reaction but can be recovered chemically unchanged at the end of the reaction |
| How do you calculate the average rate of reaction? | rate=delta q/delta t (where q is quantity and t is time) |
| How can the rate of reaction be shown to decrease over time? | By calculating the average rate at different stages in a reaction |
| How are elements in the periodic table arranged? | By increasing atomic number |
| What do elements in the same group have? | The same number of outer electrons. |
| What do elements with the same valency share? | similar chemical properties because they have the same number of electrons in their outer energy level |
| What does the nucleus of an atom contain? | protons and neutrons |
| Where are the electrons in an atom? | In the energy levels, orbiting the atom |
| What is the charge and mass of a proton? | +1, approx mass of 1 atomic mass unit |
| What is the charge and mass of an electron? | -1, almost 0 |
| What is the charge and mass of a neutron? | neural, approx 1 atomic mass unit |
| What is the atomic number? | number of protons |
| In a neutral atom, what is the number of electrons equal to? | number of protons |
| What is the mass number? | number of protons + number of neutrons |
| What is an isotope? | atoms with the same atomic number but different mass numbers - atoms with the same number of protons but different number of neutrons |
| What does nuclide notation show? | atomic number, mass number, charge so protons, neutrons and electrons can be determined |
| Most elements have 2 or more what? | isotopes |
| What is the relative atomic mass? | the average atomic mass for each element using the mass and proportion of each isotope present |
| What types of elements do covalent bonds occur in? | 2 non-metal atoms |
| When does a covalent bond form? | 2 positive nuclei are held together by their common attraction for a shared pair of electrons |
| What 7 elements exist as diatomic molecules? | H, N, F, O, I, Cl, Br |
| What are the shapes covalent molecules can be? | linear, angular, trigonal pyramidal, tetrahedral |
| What are the 2 types of covalent bonds? | covalent network and covalent molecular |
| What are some features of covalent molecular substances? | strong bonds, weak intermolecular forces, don't conduct electricity because they don't have charged particles which are free to move |
| Covalent molecular and solubility? | covalent substances which are insoluble in water may dissolve in other solvents |
| What are some features of a covalent network structure? | strong bonds and forces, very high melting and boiling points because the network is not easily broken, does not dissolve |
| In general, why do covalent network substances not conduct electricity? | they do not have charged particles which are free to move |
| When are ions formed? | when atoms lose or gain electrons to obtain the stable electron arrangement of a noble gas |
| What is the link between metal and non-metal atoms when talking about ions? | In general, metal atoms lose electrons to form positive ions and non-metal atoms gain electrons forming negative ions. |
| Ion-electron equations | Ion-electric equations can be written to show the formation of ions through loss or gain of electrons |
| What are ionic bonds? | electrostatic attraction between positive and negative ions |
| What structures do ionic compounds form? | Ionic lattice - each positive ion is surrounded by negative ions and each negative ion is surrounded by positive ions. |
| What are some features of ionic compounds? | high melting and boiling points because strong ionic bonds must be broken in order to break up the lattice, many ionic compounds are soluble in water - as they dissolve the lattice structure breaks up allowing water molecules to surround the separated ions, many ionic compounds conduct electricity only when molten or in solution as the lattice structure breaks up allowing the ions to be free to move, conduction in ionic compounds can be explained by the movement of ions towards oppositely charged electrodes. |
