504403
Descripción
Fichas por Steph Keogh, actualizado hace más de 1 año
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Creado por Steph Keogh
hace casi 11 años
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| Pregunta | Respuesta |
| What is an isotope? | An atom of the same element with a different number of neutrons. |
| What is atomic (proton) number? | The number of protons in the nucleus of an atom. |
| What is mass (nucleon) number? | The number of particles (protons and neutrons) in the nucleus. |
| What is an ion? | A positively or negatively charged atom or group of atoms. |
| What is relative isotopic mass? | The mass of an atom of an isotope compared with one twelfth of the mass of an atom of Carbon-12. |
| What is relative atomic mass? | The weighted mean mass of an atom of an element compared with one twelfth of the mass of an atom of Carbon-12. |
| What is relative molecular/relative formula mass? | The weighted mean mass of a molecule/formula unit compared with one twelfth of the mass of an atom of Carbon-12. |
| What is amount of substance? | The quantity whose unit is the mole. It is used as a means of counting atoms. |
| What is the Avogadro constant? | The number of atoms per mole of the Carbon-12 isotope. |
| What is a mole? | The amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the Carbon-12 isotope. |
| What is molar mass? | The mass per mole of a substance (units g/mol). |
| What is empirical formula? | The simplest whole-number ratio of atoms of each element present in a compound. |
| What is a molecule? | A small group of atoms held together by covalent bonds. |
| What is molecular formula? | The actual number of atoms of each element in a molecule. |
| What is molar volume? | The volume per mole of a gas. At room temperature and pressure, the molar volume is approximately 24.0 dm^3 mol^-1. |
| What is concentration? | The amount of solute, in mol, dissolved per litre of solution. |
| What is a standard solution? | A solution of known concentration. They are normally used in titrations to determine unknown information about another substance. |
| What is a species? | Any type of particle that takes part in a chemical reaction. |
| What is stoichiometry? | The molar relationship between the relative quantities of substances taking part in a reaction. |
| What is an acid? | A species that is a proton donor. |
| What is a base? | A species that is a proton acceptor. |
| What is an alkali? | A type of base that dissolves in water forming hydroxide ions. |
| What is a salt? | Any chemical compound formed from an acid when a H+ ion from the acid has been replaced by a metal ion or another positive ion. |
| What is a cation? | A positively charged ion. |
| What is an anion? | A negatively charged ion. |
| What does hydrated mean? | It refers to a crystalline compound containing water molecules. |
| What does anhydrous mean? | It refers to a substance that contains no water molecules. |
| What is water of crystallisation? | It refers to water molecules that form an essential part of the crystalline structure of a compound. |
| What is an oxidation number? | A measure of the number of electrons that an atom uses to bond with atoms of another element. They are derived from a set of rules. |
| What is oxidation? | Loss of electrons or increase in oxidation number. |
| What is reduction? | Gain of electrons or a decrease in oxidation number. |
| What is a reducing agent? | A reagent that reduces (adds electrons to) another species. |
| What is an oxidising agent? | A reagent that oxidises (takes electrons from) another species. |
| What is first ionisation energy of an element? | The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions. |
| What is electron shielding? | The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons. |
| What are successive ionisation energies? | A measure of the energy required to remove each electron in turn. |
| What is a shell? | A group of atomic orbitals with the same principal quantum number, n. Also known as the main energy level. |
| What is principal quantum number? | A number representing the relative overall energy of each orbital, which increases with distance from the nucleus. The sets of orbitals with the same n-value are referred to as electron shells or energy levels. |
| What is an atomic orbital? | A region within an atom that can hold up to two electrons, with opposite spins. |
| What is a sub-shell? | A group of the same type of atomic orbitals (s, p, d or f) within a shell. |
| What is electron configuration? | The arrangement of electrons in an atom. |
| What is a compound? | A substance formed from two or more chemically bonded elements in a fixed ratio, usually shown by a chemical formula. |
| What is an ionic bond? | The electrostatic attraction between oppositely charged ions. |
| What is a giant ionic lattice? | A three-dimensional structure of oppositely charged ions, held together by strong ionic bonds. |
| What is a group? | A vertical column in the Periodic Table. Elements in the same group have similar chemical properties and their atoms have the same number of outer-shell electrons. |
| What is a covalent bond? | A bond formed by a shared pair of electrons. |
| What is a lone pair? | An outer-shell pair of electrons that is not involved in chemical bonding. |
| What is a dative covalent/coordinate bond? | A shared pair of electrons which has been provided by one of the bonding atoms only. |
| What is electronegativity? | A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond. |
| What is a permanent dipole? | A small charge difference across a bond that results from a difference in the electronegativities of the bonded atoms. |
| What is a polar covalent bond? | A covalent bond with a permanent dipole. |
| What is a polar molecule? | A molecule with an overall dipole, when you take into account any dipoles across the bonds. |
| What is an intermolecular force? | An attractive force between neighbouring molecules. |
| What is a permanent dipole-dipole force? | A weak attractive force between permanent dipoles in neighbouring polar molecules. |
| What are van der Waals' forces? | Attractive forced between induced dipoles in neighbouring molecules. |
| What is a hydrogen bond? | A strong dipole-dipole attraction between an electron deficient hydrogen atom on one molecule and a lone pair of electrons on a highly electronegative atom on a different molecule. |
| What is metallic bonding? | The electrostatic attraction between positive metal ions and delocalised electrons. |
| What are delocalised electrons? | Electrons that are shared between more than two atoms. |
| What is a giant metallic lattice? | A three-dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds. |
| What is a simple molecular lattice? | A three-dimensional structure of molecules, bonded together by weak intermolecular forces. |
| What is a giant covalent lattice? | A three-dimensional structure of atoms, bonded together by strong covalent bonds. |
| What is a period? | A horizontal row of elements in the Periodic Table. Elements show trends in properties across a period. |
| What is periodicity? | A regular periodic variation of properties of elements with atomic number and position in the Periodic Table. |
| What is thermal decomposition? | The breaking up of a chemical substance with heat into at least two chemical substances. |
| What is a displacement reaction? | A reaction in which a more-reactive element displaces a less-reactive element from an aqueous solution of the latter's ions. |
| What is disproportionation? | The oxidation and reduction of the same element in a redox reaction. |
| What is a precipitation reaction? | The formation of a solid from a solution during a chemical reaction. Precipitates are often formed when two aqueous solutions are mixed together. |
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