Elements and Compounds

Iron sulphate/ iron sulphite.

Iron(II) sulphate(Ferrous sulphate) is FeSO4 ; Iron in is oxdation state '2' (II). Iron(III) sulphate(Ferric sulphate) is Fe2(SO4)3 ; Iron in is oxdation state '3'(III)

Iron(II) sulphite(Ferrous sulphite) is FeSO3 ; Iron in is oxdation state '2' (II). Iron(III) sulphite(Ferric sulphite) is Fe2(SO3)3 ; Iron in is oxdation state '3' (III).

For the second part , note the spelling and the number of oxygen's present.

Same as the solid ' MgCl2 ', its just that the molecules are further apart.

MgCO3 is Magnesium Carbonate.

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Nitrogen.

Molecular mass of N2 = 14 x 2 = 28

Molecular mass of O2 = 16 x 2 = 32

32 > 28 Hence oxygen is heavier than nitrogen.

NB CO2 is heavier again. Molecular mass is 12 + ( 2 x 16) = 44

So CO2 fall to the ground and is absorbed by 'green' plant life to form oxygen and biomass.

It is a dangerous radio-active metallic Group '1' element.

It will react explosively with water. The spray from the explosion is also radio-active, so you will not find it in a school/college/university lab.

It is kept under very controlled conditions.

Chlorine gas is bubbled through fresh water.

In doing so it 'disproportionates' , that is it forms two ions Cl^(-) and Cl^(+).

These two ions combine with a molecule of water to form HCl(aq) & HClO(aq)

Cl2(g)= Cl^(-) + Cl^(+)

Cl^(-) + Cl^(+) + H2O = HC(aq) + HClO(aq)

Both are bacteriocides.

HCl is hydrochloric Acid and HClO is Hypochlorous acid (Bleach ion).

There are sufficiently weak that they do not harm humans from the public water supply, but the 'bugs' are 'dead/killed'.

Brimstone' is an archaic(historical) word for sulphur.

Sulphur being an element , found in the Periodic Table under 'S', hence it follows that 'brimstone' is an element.

Three elements are present.

They are

Calcium(Ca) , Carbon(C) , and Oxygen(O).

The chemical formula for calcium carbonate is ' CaCO3 '.

This tells us that there are ;-

1 atom of the element Calcium

1 atom of the element Carbon

3 atoms of the element Oxygen.

K2S is the formula for the ionic compound formed from potassium and sulfur.

NaBr is sodium bromide.

Na is the symbol for sodium ( from the Latin for sodium , which is 'Nadium').

Br is the symbol for bromine .

No, acids and alkalis do not react in a combustion reaction. Combustion is a chemical reaction that involves a substance combining with oxygen to produce heat and light. Acids and alkalis react in neutralization reactions, where they form water and a salt.

Calcium carbonate contains three elements. viz. Calcium, Carbon , and Oxygen.

The chemical formula is ' CaCO3 '.

This tells us that a molecule of calcium carbonate conrains ;-

1 x Calcium(Ca)

1 x Carbon(C)

3 x Oxygen(O3)

Thereby one molecule of calcium carbonate contains 3 elements and 1 + 1 + 3 = 5 atoms.

There are three elements in calcium carbonate viz.

Calcium(Ca) , Carbon(C) and Oxygen(O)

The formula for calcium carbonate is 'CaCO3 '.

This tells us that there are ; -

1 x calcium (Ca)

1 x carbon (C)

3 x oxygen (O3)

atoms present in this compound.

Limestone, Chalk, and Marble are naturally occurring minerals, which are impure forms of calcium carbonate.

Iron Sulphate is in two oxidation states.

#1 ; Ferrous sulphate; Iron(II) sulphate ' FeSO4

#2 ; Ferric sulphate; Iron(III) sulphate ' Fe2)SO4)3.

In Ferrous sulphate ; FeSO4

There are

1 x Iron(Fe)

1 x Sulphur(S)

4 x Oxygen(O4)

There are three elements present and six atoms.

In Ferric sulphate ; Fe2(SO4)3

There are

2 x Iron(Fe2)

3 x Sulphur(S ; 1 x 3 )

12 x Oxygen(O ; 4 x 3 )

There are three elements present and seventeen atoms.

NB The symbol for iron is 'Fe' from Latin for iron ,which is 'Ferrum'.

NNB The '3' after the brackets indicates that everything inside the brackets is multiplied by '3'.

The molecular formula for Ammonium Sulphate is (NH4)2SO4.

Ferrous sulphate, or iron (II) sulphate has the formula FeSO4.

It oxides to white calcium oxide (CaO).

Calcium is a reactive metal , and will react with oxygen in the air fairly quickly to form calcium oxide

2Ca(s) + O2(g) = 2CaO(s)

Calcium oxide is a white solid, and commonly known as 'lime'.

NB Groups '1' & '2' elemental metals react with oxygen(air)to form the corresponding oxide.

The vigorousness of the reaction varies, but usually you can see it happen over a period of seconds/minutes.

Electron (-1)

Positron (Positive electron) (+1)

Neutron ( 0 )

Proton ( +1)

NB A positron is a particle of an electrons mass, much less than a proton, but has a positive charge.

Ferrous sulphate is FeSO4 ; Iron (II) sulphate

Do NOT confuse with Ferric Sulphate , which is ' Fe2(SO4)3 '; Iron(III) sulphate

In Ferrous compounds iron is in Oxid'n state '2' (II). Green in colour

In Ferric compounds iron is in Oxid'n state '3' (III). Red/brown in colour.

NB THe oxid'n number is ALWAYS quoted in Roman Numerals.

Yes, energy is released in a sodium and chlorine reaction as they form sodium chloride (table salt) due to the formation of new chemical bonds which are more stable than the individual sodium and chlorine atoms. This release of energy is typically in the form of heat.

' +6'

To calculate the oxidatioin state. use oxygen at '-2' as the standard.

There being four oxygen atoms in SO4^(2-)

Then the oxygen moiety is 4 x -2 = -8

Since the overall charge on the anion is ;-2'

We create a little sum

S + -8 = -2

S - 8 = -2

Add '8' to both sides

S = -2 + 8

S = +6 (The oxidation state of sulphur in SO4^(2-) .

NB Sulphur has variable oxidation states, ranging from -2,0,2,4, & 6.

NNB The oxidation number indicates the number of electrons in the valence(outermost) shell involved in bonding. Not all electrons in the valence shell are used in bonding.

This method is good for calculating other oxidation states. e.g. potassium manganate (VII) : KMnO4.

What is the oxidation state of manganese. ? It is ;7; (VII).

How do we go there>

Again remeber oxygen at '-2' and the manganese anion is MnO4^(-)

So 4 x -2 = -8

Create the sum

Mn + - 8 = -1 (The charge on the anion).

Add '8' tpo both sides.

Mn = -1 + 8

Mn = 7 (The oxidation state of manganese in MnO4^(-) .

NNNB All oxidation numbers are quoted as Roman Numerals. . Hence S is (VI) ' 6' and Mn is (VII) '7'.

YES!!!

However, it has to be heated up .

All elements and nearly all compounds can exist in solid liquid or gaseous state.

The critical factors for changes of state are temperature and gas pressure above the substance.

NB Carbon dioxide (gas) sublimes directly to a solid (dry ice) when cold enough. However, this is atmospheric gas pressure. If the gas pressure is altered then it can be converted to a liquid.

Beryllium.

Its full electron configuration is ' 1s2, 2s2 , '.

It depends on the type of plastic and the type/strength of the acid.

Many plastics such as polyethylene (PE) and polypropylene (PP) are resistant to many common acids.

Some plastics can react, weaken, dissolve, crack, or degrade when exposed to strong acids or certain chemical conditions.

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