T2- s Block LP1 + LP2 Flashcards
What are alkali metals?
Group 1 elements
What are relativistic effects?
As the element gets heavier, those electrons going around approach the speed of light. This makes them heavier, and their increased mass perturbs the energy levels that apply to electronic transitions, and actually it moves it into the visible region.
Using flame test, what colour is lithium?
Crimson

Using flame test, what colour is sodium?
Yellow
Using flame test, what colour is potassium?
Red to violet
Using flame test, what colour is rubidium?
Violet
Using flame test, what colour is caesium?
Blue
Why flame tests give colours?
Alkali metals give electronic transitions in the flames which fall in the visible part of the spectrum.
For what you can use flame test?
To identify alkali metals and intensity can be measures quantitatively using a flame photometer.
What are chemical properties for alkali metals?
Low first ionisation energym very reactive, going down the group atomic radius increases that leads to increase in ionisation energy forming M+ ions more readily doen group.
Describe alkali metal reaction with water.
Reaction is very exothermic and increases in violence from the lightest to the heaviest elements in the group.
Why alkali metals must be stored under hydrocarbon oil?
To prevent reaction with atmospheric oxygen. Li, Na and K can be handled in air for short periods, Rb and Cs must be handied under an inert atmosphere at all times.
Why Li+ can exhibit a high degree of covalent character?
Because it has a very high charge density on a very small cation. So it can distort the electron clouds of anion towards itself, crating greater covalent bonding.
Why alkali metals exept Li form ionic compounds?
They are heavier, they are not very polarising.
Why metallic bonding is weak for alkali metals?
Becaus ethey have only one electron in valence shells which contributes to molecular orbital band.
What are azides?
Compound with present N3

For what hydrides are used in reactions?
They react vigously with water.
NaH +H2O —> NaOH +H2
Used as reagents for the synthesis of othe compounds.
4LiH +SiCl4 —-> SiH4 + 4LiCl
Usefull as non-nucleophilic bases and reductants.
NaH + NH3—> NaNH2 +H2
What are halides?
Inorganic compounds with formula MX. Colourless crystalline solids, with high melting temperature. All of the halides (exept LiF) soluble in water to give ionic solutions.
When generally solubility is the highest?
When there is large difference in radius between the cation and the anion.
What is formed when Li reacts with O?
Lithium oxide
What is formed when Na reacts with O?
Sodium peroxide
What is formed when K reacts with O?
Potassium superoxide, O2-
What is Kapustinskii equation for lattice energy?
