redox and group 2

oxidation number

a measure of the number of electrons that one atom uses to bond with atoms of another element. They are deprived from a set of rules

oxidation

loss of electrons or increase in oxidation number

reduction

gain of electrons or decrease in oxidation number

redox reaction

a reaction involving a reduction and an oxidation

OIL RIG

Oxidation Is Loss Reduction Is Gain

what is the oxidation number for elements

0

what is the oxidation of diatomic molecules

0

where is the sign placed for oxidation numbers

before the number

what is the oxidation number of ionic compounds

same as ionic charge but the sign comes before the number

oxidation number of oxygen

-2

oxidation number of hydrogen

+1

oxidation number of Fluorine

-1

oxidation number of Na+

+1

oxidation number of Mg 2+

+2

oxidation number of Cl-

-1

oxidation number of H in metal hydrides (NaH2)

-1

oxidation number of O in peroxides (H2O2)

-1

oxidation number of O bonded to F (F2O)

+2

what is always the sum of oxidation numbers

the total charge

oxidation number of sulfur in H2SO4

+6

oxidation number of nitrogen in NO3-

+5

what do Roman numeral show

the oxidation state of an element

what does Iron (II) represent

Iron with an oxygenation number of +2

what is the oxidation number of NO2- and therefore what is it called

+3 - nitrate (III)

oxidation number of NO3- and therefore what it is called

+5 - nitrate (V)

what do dilute acids undergo redox reactions to form

salts and hydrogen gas

what is oxidised and what is reduced in Zn + 2HCL -> ZnCl2 +H2

-Zinc is oxidised from Zn with an oxidation number of 0 to ZnCl2 with an oxidation number of +2
-hydrogen is reduced from HCL with an oxidation number of +1 to H2 with an oxidation number of 0

what kind of compounds to group 2 metals form

stable compounds

are group 2 metals reactive or unreacitve

reactive

why are group 2 metals reducing agents

-each metal atom is oxidised by loosing 2 electrons to from a 2+ ion
-another species will gain 2 electrons and be reduced
-this makes it a reducing agent

how do group 2 metals react with oxygen

-form a metal oxide with the general formula MO

how do group 2 metals react with water

-form a alkaline hydroxide with the general formula M(OH)2 +H2

how do group 2 metals react with acids?

-they form a salt and hydrogen

what is the trend in reactivity in group 2?

increases down the group

what is the trend in ionisation energies in group 2 and why?

-decreace down the group
-becuase nucelar attraction decreases because of larger atomic radius and more electron shielding. second ionisation energy decreases

what happens when a group 2 metal reacts with water

-releases hydroxide ions forming an alkali solution. a metal hydroxide is formed.

are the metal hydroxides formed when a group 2 metal reacts with water soluble or insoluble

-slighly soluble
-when saturated there is solid precipitate

what is the trend for the solubility of hydroxides down the group

-solublity increases down the group

oxidation numbers of oxygen and Barium in BaO2

Ba= +2 O= -1

what can the oxidation number never be higher than

the group number of the element

what is a disproportionation reaction

when the same element is oxidised and reduced

draw H2O2

which group 2 metals can be used for antiacids and why

the top ones, low concentration of OH- ions, not too alkali

how are group 2 metals used in agriculture

neutralise acidic soil