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Description
Flashcards by Jasmine Wells, updated more than 1 year ago
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Created by Jasmine Wells
about 9 years ago
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| Question | Answer |
| Define atomic radius | The total distance from an atoms nucleus to the outermost orbital of an electron. |
| Define ionic radius | The radius from an atom forming an ionic bond. |
| Define ionisation energy | The amount of energy required to remove one electron from one mole of gaseous atoms to produce on mole of gaseous ions. |
| Electron Affinity | The change in energy (kj/mole) of a neutral atom (in the gaseous phase) when an electron is added to the atom to form a negative ion. |
| Define electronegativity | Is a measure of the tendency of an atom to attract bonding pair of electrons. |
| Covalent radius | Radius of two non metallic atoms bonded together given by the equation Rb= 1/2d - Rb = bonding atomic radius - D = distance between two nucleus |
| List trends of atomic radius across a period | Across a period atomic radii decreases. This is because an increasing effective nuclear charge. The greater the eff nuclear charge pulls valence electrons closer to nucleus reducing radius. |
| Trend of atomic radius increases | Outer shell electrons enters new energy level, so are further away from the nucleus. |
| What is an ion? | An ion is a charged species and can either be cations or anions. |
| What is a cation | Positively charged. Metals usually form positively charged ions. |
| What is an anion? | Negatively charged ion. Non-metals are usually form negatively charged ions. |
| Describe ionic radius of cations | Radii of cations are smaller than parent atoms due to there being more protons than electrons, so valence electrons are more strongly attracted to nucleus. |
| Describe ionic radius of anions | Radii of anions are larger than their parent atoms due to there being more electrons than protons, resulting in greater repulsion between valence electrons. |
| Ionisation energy trends across a period | Ionisation energy increases across a period. 1) Effective nuclear charge increases across a period, meaning valence electrons are pulled closer to the nucleus. The attraction between electrons and nucleus making it more difficult to remove one electron. 2) Atomic radii decreases across a period - making it more difficult to remove one electron |
| Ionisation energy trends down a group | Ionisation energies decreases going down a group. 1) Atomic radii increases down a group making it easier to remove an electron 2) Shielding effect of core electrons weakens the attractive force between nucleus and outer electrons. |
| Electron affinity trends across a period | Electron affinity values become more negative across a period |
| Electron affinity trends down a period | Electron affinity generally becomes less negative down a group |
| Electronegativity trends across a period | Electronegativity increases due to an increase in effective nuclear charge and atomic radius |
| Electronegativity trends down a group | Electronegativity values decrease because of an increase in atomic radius and decrease of effective nuclear charge. |
| Metallic trends across a period and down a group | Across a period: Metallic character generally decreases across period, increases down a group |
| Why do non metals have a highly negative electron affinity? | Because they tend to gain electrons during chemical reactions (reduced) |
| Are metals oxidises or reduced? | Oxidised - because they lose electrons. |
| How is an oxide formed? | From the combination of an element with oxygen |
| Are metal oxides acidic or basic? | They are basic. They react with water to form metal hydroxides. |
| Are non-metal oxides basic or acidic? | Non-metal oxides are acidic. They react with water to form acidic solutions. |
| What is an amphoteric property? | A chemical species that behave both as an acid and a base. E.g. Aluminium oxide |
| What is an amphioprotic oxide? | Proton donors or proton acceptors. |
| How do period 3 oxides vary across a period? | Left - Basic Middle - Amphoteric Right - Acidic |
| List 4 properties of group 1 (alkali metals) | - One valence electron - Form positive ionic compounds - they are oxidised - reactions of alkali metals with water is more rigorous down the group 1 - Group one react with water to form metallic hydroxide - producing an alkaline solution. |
| List 4 properties of group 17 (Halogens) | - Seven valence electrons - tendency to gain electron to complete full shell - Form Ionic compounds with metals - Covalent compounds with non-metals - Highly reactive but reactivity decreases down group. |
| What happens when a halogen reacts with an alkali metal? | They form ionic alkali metal salts. E.g. NaCl |
| What are the 5 main properties of transition metals? | - Forms coloured compounds -Exist in variable oxidation states - Can often act as catalysts in chemical reactions - Contain magnetic properties - Form complexes with co-ordinated ligands. |
| Define a transition metal. | Are elements with an incomplete d-subshell. |
| What are the 2 NON Transition elements? | Scandium (Sc) Zinc (Zn) |
| Why isn't scandium considered a transition element? | Has no electrons in "d" orbital - Sc has electronic structure [Ar]3d 4s2. When ions form, Scandium loses 3 outer shell electrons, ending up with Argon structure. |
| Why is zinc not considered a transition element? | Has full "d" sub level - Zn is not a transition metal because it forms only Zn2+ ions with all the 3d electrons present. |
| Why are transition metals different colours? | D-orbitals are split into 2 distinct levels. The energy levels between 2 wavelengths corresponds to a particular wavelength frequency in the visible light spectrum. |
| How can transition metals form variable oxidation states? | Due to successive ionisation energies that occur in transition metals, transition metals are able to form variable oxidation states. |
| What is a complex ion? | A compound that consists of a metal ion at its centre, bonded via coordinated bonding to a group of molecules or ions known as ligands. |
| What is a ligand? | An atom, molecule or ion which contains a lone pair of electrons, that coordinates, through coordinated bonding to form a complex ion. |
| What are the two types of ligands? | Monodenate ligands Polydenate ligands (chelate ligands) |
| What is a monodenate ligand? | - Contains a single donor atom and have one lone pair contributing to the coordinate bond in a complex. E.g. water (H20) |
| What is a polydenate ligand? | Have two or more donor atoms that for coordinate bonds with a transitional metal centre. |
| What is the coordination number? | The amount of ligands that are attached/bonded to the transitional metal ion. |
| How can transition metals exhibit magnetism? | Complexes and transition metals that contain unpaired electrons. |
| What are the 3 ferromagnetic elements? | Iron, cobalt and nickel |
| What is ferromagnetism? | A permanent type of magnet - e.g. iron |
| What is paramagnetism? | Are transition metals that contain unpaired electrons behaving like tiny magnets and are attracted by an external magnetic field. |
| How does paramagnetism work? | The spinning unpaired electrons create a small magnetic field and will line up in an applied electric or magnetic field. Transition metal reinforce the external magnetic field. The more the unpaired electrons available, the more paramagnetic the complex will be. |
| What is a diamagnetic property? | Are transition metals that do not contain unpaired electrons and are repelled by external magnetic fields. |
| Why are transition metals often used as catalysts? | Because their compound behaviour makes a very efficient catalyst. |
| What are the catalysts used for? | Industrial processes. e.g. production of Ammonia (Haber process) |
| State 4 industrial processes | - Haber process -Contact process - Hydrogenation reactions - Manganese oxide with hydrogen peroxide |
| What is the transition metal used in the haber process? | Iron |
| What is the transition metal used in the contact process? | Vanadium |
| What is the transition metal used in hydrogenation reactions? | Nickel |
| What is a homogenous catalyst? | Catalysts that are in the same phase or physical state as the substances involved in the reaction that it is catalysing e.g. aqueous |
| What is a heterogenous catalyst? | Heterogenous catalyst is one that is in a different phase/state to substance that it is catalysing. - Transition metals used in industries are usually heterogenous. |
| What is the crystal field theory? | Is a model that describes the breaking of orbital degeneracy in transition metal complexes due to presence of ligands. |
| What is crystal field splitting energy | The energy separation between the two split split degenerate sets of orbitals. |
| What are the factors that affect the crystal field splitting energy? | - Identity of metal ion -Nature of ligand |
| Describe the process of the crystal field theory. | - When a complex ion is formed, the ligands that attach to the metal ion centre has a pair of lone electrons. - The pair of lone electrons that bond through coordinated bonding causes a repulsion as it enters the same plane as valence electrons - The repulsion causes the valence electrons to split into 2 distinct levels - The energy level between 2 wavelengths corresponds to a particular frequency in visible light spectrum. (As light is absorbed when electron is excited between the d-orbitals) - The colour absorbed is complementary to the colour observed. |
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