Chemistry- Group 2

what is group 2 known as, also include details of atomic structure

the alkaline earth metals, have 2 valence electrons, occupy a sub shell

describe the trend of metallic radius down group 2

increases down the group, shells further away from the nucleus

describe the trend of melting point down the group

melting point decreases down a group, due to a weaker metallic bond as distance between positive nucleus and electrons on outer shells grows

describe the trend of density down a group

density increases down the group due to the general increase in density

what compounds do group 2 elements form

form ionic compounds, acting as reducing agent as they readily donate their 2 valence electron as they undergo oxidation.

why are group 2 elements so good to use to reduce other elements

because of their low electronegativity, and low ionisation energies

what is the trend of first ionisation energies down group 2

ionisation energies decrease; higher shielding, higher atomic radius etc

trend of reactivity down group 2

increases down group, is easier to lose the two valence electrons than gaining 6

what is the general equation for metals reacting with acids, which group 2 follows

metal + acid —> metal salt + hydrogen gas

write out the reaction of all the group 2 elements with HCl

refer to cheat sheet

write down all the group 2 reactions with H2SO4

refer to cheat sheet

which sulfate products are insoluble from these reactions, give reason why

CaSO4, SrSO4, BaSO4; because the solubility of sulfates decreases going down the group

describe the nature of the reaction between group 2 and HCl

all of the elements react vigorously

describe the nature of the reactions of group 2 elements with H2SO4

refer to cheat sheet, various reason for different rates of reactions

what do group 2 elements react with oxygen to form, state the general equation

they form white solid oxides, 2Mg + O2 —> 2MgO

which elements from group 2 react with oxygen to form peroxides

strontium, barium

write out reactions of group 2 elements with oxygen

refer to cheat sheet

what does a magnesium compound give off in flame tests

doesn’t typically burn with colour

what does magnesium metal give off for flame test

bright white flame

what do calcium compounds give off with flame test

brick red colour

what do strontium compounds give off for flame test

scarlet/red colour

what colour do barium compounds give off for the flame test

apple-green colour

what do group 2 elements form when react with water, with the exception

form metal hydroxides, except beryllium

describe the solubility and the precipitates formed by the hydroxides

form a white ppt, solubility increas3es down the group, magnesium and calcium considered insoluble

what is the general equation for group 2 reacting with water

M + 2H2O —> M(OH)2 + H2

which group 2 element also reacts with steam, provide equation

Magnesium; Mg + H2O —> MgO + H2

write out the group 2 elements reacting with water

refer to cheat sheet

when are group 2 oxides formed

when the metals are burnt in oxygen

what solution is formed when group 2 oxides react with water

form an alkaline solution

list all the reactions of group 2 oxides reacting with water

refer to cheat sheet

refer to cheat s

describe the observation seen with MgO reacting with water

Mg is only slightly soluble in water, so forms pH 10

describe the observation seen with CaO reacting with water

is a vigorous reaction, releases a lot of energy, pH 11

what is another name for calcium hydroxide

lime water

write the general equation for metal oxide with HCl

metal oxide + HCl —> salt + water

write general equation for metal oxide with sulfuric acid

metal oxide + sulfuric acid —> sulfate + water

when metal oxides react with H2SO4, does it form a soluble or insoluble compound

forms insoluble

write the reactions of the metal oxides with HCl

refer to cheat sheet

write out the reactions of metal hydroxides with dilute sulfuric acid

refer to cheat sheet

write out the reaction of the group 2 carbonates with Hcl

refer to cheat sheet

what is the general equation of group 2 carbonates with HCl

metal carbonate + HCl —> metal chloride + carbon dioxide + water

write the general equation for group 2 carbonates with sulfuric acid

metal carbonate + sulfuric acid —> metal sulfate + hydrogen + carbon dioxide

define thermal decomposition

the breakdown of a compound by heat into two or more different substances

what happens when you heat a group 2 carbonate

breaks down into metal oxide and carbon dioxide

describe the trend in thermal stability of group 2 carbonates and nitrates and why

thermal stability increases down group 2 requiring more heat to break down, The carbonate ion is easily polarised by a small highly charged cation (Mg²⁺ therefore polarises it the greatest) which weakens the bond between carbon and oxygen.

write the general equation for when group 2 carbonates are broken down by thermal decomposition

XCO3 —> XO + CO2

write the 2 general equation for the thermal decomposition of group 2 nitrates

2X(NO3)2 —> 2XO + 4NO2 + O2

or X(NO2)3 —> XO + 2NO2 + ½ O2

what is nitrogen dioxide gas observed as

brown fumes, toxic

list some of the uses of group 2 metals

eg calcium compounds:

• calcium oxide; used to neutralise acidic soil

• calcium carbonate; used as building material

does alkalinity increase or decrease going down the group for hydroxides, why

alkalinity increases as solubility increases down the group, meaning it will produce more hydroxide ions in this equation: O^2- (aq) + H₂O(l) → 2OH^- (aq)

list the solubility of the group 2 hydroxides at 298 K mol

refer to table on cheat sheet

write the general equation for hydroxide dissolving in water

X(OH)₂ (aq) → X²⁺ (aq) + 2OH^– (aq)

write the general equation for how a sulfate dissolves in water

XSO₄ (s) → X²⁺ (aq) + SO₄^2- (aq)

does solubility of group 2 sulfates increase or decrease going down the group

it decreases going down the group, enthalpy of hydration decreases, making it less attracted to water molecules and harder to break down