AS CHEMISTRY 9701 with complete solutions

Define: atomic number. The atomic (proton number) is the number of protons in the nucleus. Define: mass number. The mass (nucleon) number is the total number of protons and neutrons. 01:21 01:39 Define: First Ionisation energy. The first ionisation energy is the energy needed to remove one mole of electrons from one mole of gaseous atoms to form one mole of ions wih a single positive charge. example: X(g) - X+(g) + e- Define: Relative molecular mass. The relative molecular mass of a compound is the mass of its fomula unit - relative to 1/12 the mass of an atom of carbon-12. Define: theoretical yield. Theoretical yield is the maximum amount of product that can be made from the available reactancts. (This is calculated from the amounts of the reactants using the balanced equation.) percentage yield = ( actual yield / theorectical yield ) x 100 Define: Actual yield. The Actual Yield is the amount of product that is actually made/measured at the end of the reaction. percentage yield = ( actual yield / theorectical yield ) x 100 Define: first electron affinity. The first electron affinity is defined as the energy change when one mole of gaseous atoms accepts one mole of electrons to form one mole of ions with a single negative charge. X(g) + e- - X-(g) Define: electronegativity. Electronegivity is the power of an atom to attract electrons towards itself in a covalent bond. Define: molecular orbital. An orbital is the area of space where an electron is most likely to be found. Define: Mole. One mole is the amount of substance that contains as many particles as there are atoms in exactly 12g of carbon-12. The number of particles in one mole is 6x10^23 (Avogadro's constant.) Note: the relative atomic mass in grams of any element contains one mole of atoms. Define: the standard enthalpy change of combustion. ∆H⊖c The standard enthalpy change of combustion is the enthalpy change when one mole of a substance burns completely in oxygen under standard conditions.