Structure 3 Flashcards
(65 cards)
Periodicity
A repeating pattern in the chemical and physical properties of elements - when elements are arranged according to their atomic number
Across a period, atomic radius
Decrease
Down a group, atomic radius
Increase
Positive ions have (bigger/smaller) radius than the atom it’s derived from
Smaller
Isoelectronic positive ions (increase/decrease) in size across a period
Decrease
Isoelectronic
Same number of electrons
Negative ions have (smaller/larger) radius than the atom they are derived from
Larger
Isoelectronic negative ions (increase/decrease) across a period
Decrease in size across a period
What is ionisation energy?
The enthalpy change when an electron is removed from an atom in the gaseous state
Is removing an electron an exothermic or endothermic process?
Endothermic
Across a period, the electrons are more difficult to remove because ..
The increase in the nuclear charge increases the attraction between the nucleus and the valence electron
Down a group, the electrons are easier to remove because …
There is an increased distance between the valence electron and the nucleus
Electron affinity
The enthalpy change when an electron is added to an isolated atom in the gaseous state
Electron affinity equations must include
States
Electron affinity values generally increase …….. and ……..
Across a period and up a group
What is electronegativity?
A relative measure of the attraction that an atom has for a shared pair of electrons when it is covalently bonded to another atom
Does electronegativity apply to all groups?
No not group 18
Across a period, electronegativity (increases/decreases) due to ….
Increases, the increase in nuclear charge
Down a group, electronegativity (increases/decreases) due to ….
Decreases, the bonding electrons are furthest from the nucleus
Physical properties of alkali metals
- Good conductors of electricity and heat
- Low density, can float on water
- Shiny grey surfaces when freshly cut
Chemical properties of alkali metals
- Very reactive
- Form ionic compounds with non-metals
Physical properties of halogens
- Coloured
- Show a gradual change from gases, to liquids, to solids
What 2 halogens are gases?
F2 and Cl2
What halogen is a liquid?
Br2