| what is periodicity? | the occurrence of patterns in the periodic table |
| what is a group in the periodic table | a vertical column containing element with similar chemical properties and the same number electrons in the outer shell |
| what is a period in the periodic table? | rows of elements arranged with increasing atomic numbe |
| what is covalent radius | half the distance between the nuclei of two bonded atoms of the element; gives a measure of the size of an atom |
| what is the trend in covalent radius across period | decreases number of protons in nucleus increases across a period higher nuclear charge higher electrostatic attraction between electrons and nucleus atom becomes smaller |
| what is the trend in covalent radius down a group | increases no. of occupied energy levels increases down a group less electrostatic attraction between electrons and nucleus atom size increases |
| what is first ionisation energy | The first ionisation energy is the energy required to remove one electron from each atom of one mole of gaseous atoms. |
| what can first ionisation energy of any element be represented by in a chemical equation | M(g) → M+(g) + e- |
| What is second ionisation energy | energy required to remove one electron from each singly positive ion of one mole of the gaseous ions. |
| how can the second ionisation energy of any element be represented in a chemical equation | M+(g) → M2+(g) + e- |
| why are ionisation energies endothermic? | Energy is required to remove an electron from any atom because there is an attractive force between the nucleus and the electron being removed which has to be overcome. |
| what is the trend in ionisation energy across a period | increases no. of protons in nucleus increases across a period increased nuclear charge greater electrostatic attraction between nucleus and electrons more energy required to remove electrons |
| what is the trend in ionisation energy down a group | decreases number of energy levels increases going down a group electron being removed is further from the nucleus electron is more shielded from nucleus by inner energy lefvels weaker electrostatic attraction between electrons and nucleus less energy required to remove electron |
| why are second and third ionisation energies larger than the first | the extra positive nuclear charge has greater electrostatic attraction for the outer electrons and therefore more energy is required to remove subsequent electrons. |
| why is the second ionisation energy of alkali metals much higher than the first | The second ionisation energy is much higher than would be expected because this electron is being removed from a full outer energy level which is:
a very stable arrangement
closer to the nucleus
less screened from the nucleus as there are fewer inner
electron energy levels. |
| what is electronegativity | Electronegativity is a measure of the attraction an atom involved in a bond has for the electrons of the bond. |
| what is the trend in electronegativity across a period? | increases the nuclear charge increases nucleus has a stronger electrostatic attraction for electrons |
| what is the trend in electronegativity down a group? | electronegativity decreases atomic size increases due to the increase in the number of occupied energy levels electrons are further from the nucleus nucleus is more screened by inner occupied energy levels electrostatic attraction between the nucleus and electrons is reduced |
