Ions Are Atoms, Which Have Gained Or Lost Electrons, in Order to Become More Stable It

Ions

Ions are atoms, which have gained or lost electrons, in order to become more stable – it happens during chemicalreactions.

Ions always have a charge

-Positively charged ions have fewer electrons than protons – also called cations.

-Most metals form cations – that means they lose electrons

e.g. Li1+

Li loses an electron

Li1+

-Negatively charged ions have more electrons than protons – also called anions.

-Non-metals that form anions have a name ending in ‘ide’

e.g. chloride (Cl-), oxide (O2-)

All non-metals gain electrons (that is, form anions).

Compounds

Compounds are formed when two or more elements are chemically combined.

Noble gases with their 8 valence electrons are very stable elements – they usually don’t form compounds.

Other atoms have different ways of becoming stable – they either gain or lose electrons when they form compounds.

-**Metals give up electrons to other atoms, forming cations.

-**Non-metals accept electrons, forming anions.

-**Non-metals may share electrons with other atoms.

e.g. Sulphur dioxide

non-metalnon-metal

There are two basic types of compounds:

Molecular
Ionic

Molecular Compounds

Atoms which shareelectrons to become stable form molecular compounds

These groups of atoms are called molecules

Atoms in molecules are joined by covalent bonds.

All atoms in molecular compounds are non-metals.

Molecularcompounds – non-metal and non-metal joined chemically.

e.g. CO2

Naming and Writing Binary Molecular Compounds

-When two(binary) non-metallic atoms join by a covalent bond we have a molecular compound.

e.g. Carbon dioxide

Rules for naming

The first element in the compound is the one most left on the periodic table.

The suffix ‘ide’ is attached to the name of the second element.

Prefixes are used to indicate how many atoms of each type are present in one molecule of the compound.

Prefixes:

1 = mono6 = hexa

2 = di7 = hepta

3 = tri8 = octaMEMORIZE

4 = tetra9 = nona

5 = penta10 = deca

No “mono” is used with the first element.

e.g. Give the name or formula for each compound:

NO2 – Nitrogen dioxide

N2O – Dinitrogen monoxide

N2O4 – Dinitrogen tetraoxide

Nitrogen monoxide - NO

Dinitrogen pentaoxide – N2O5

Carbon dioxide – CO2

Assignment:

Name or give the formula:

Silicon dioxide
Sulphur monoxide
OF2
SiBr4
PH3
N2O
CO
NBr3
P2I3
SO3
N2O4
Tetraphosphorous hexaoxide
Dinitrogen tetraoxide
Heptasilicon monobromide
Octaboron decaiodide
B2O3
BrF7
N3O6
H2Cl5
Triselenium diastatide
Diarsenic pentaoxide
Sulphur trioxide
C3O2
C2H6
As3Br7
SO2
Selenium monoxide
Diboron trioxide
PF3
P2O5
P4O10
Arsenic trifluoride
BrF7
Hydrogen chloride
N2O
p. 14 #1

Binary Ionic Compounds

Are composed of ions of one metal element and ions of one non-metal element joined by ionic bonds

Rules for naming

The first element in the name of the formula is the metal
The second element, the non-metal, is named as an ion. The suffix ‘ide’must be present.
No prefixes are used.

e.g.

Fe2O3 – Iron oxide

CuS – Copper sulfide

KCl – Potassium chloride

Writing Formulas for Binary Ionic Compounds

In an ionic compound the total number ofpositive chargesmustequalthe total negativecharges – the compound must be electrically neutral.

This fact tells us how many of each atom is necessary to form a compound.

e.g. sodium chloride

Step 1 – use the table to find the charges on each ion (element)

Na1+Cl1-

Step 2 – bring the two ions close together and see what the net charge is.

Na1+Cl1- the two charges are equal so the formula is NaCl

Magnesium chloride

Mg2+Cl1-

Question: how many of each ion is needed so that the molecule is neutral.

Cl1-

Mg2+

Cl1-

Therefore the formula is MgCl2

Chromium oxideCr3+O2-

Cr3+O2-to balance the charges we use a shortcut method – charges are “traded” across.

Cr2O3

Calcium oxide Ca2+O2- Ca2O2CaO

Multivalent Cations(metals)

-Some atoms are able to form more then one cation. Ex. Ni2+ or Ni3+

-In the Stock system, the charge on the cation is written in brackets, as a Roman numeral after the name of the metal

Example

Copper (II) oxideCu2+O2- CuO

Tin (IV) fluorideSn4+F1- SnF4

PbI2 Lead (II) iodide

Pb2+ I1-

Cr2S3Chromium (III) sulfide

Cr3+S2-

Is this formula correct LiOLi1+O2-

No – correct formula is Li2O

Assignment: Name or write the formula for the following compounds:

tin (II) fluride
lead (IV) oxide
iron (III) oxide
iron (III) sulphide
potassium chloride
sodium oxide
lead (II) oxide
SbBr5
PbBr2
NaF
sodium bromide
iron (III) fluoride
sodium chloride
lithium nitride
silver oxide
magnesium bromide
barium chloride
potassium iodide
zinc sulphide
copper sulphide
p. 11 #1

Review – Naming Molecular and Ionic CompoundsName ______

Binary molecular compound: Use prefixes for naming.

Write the formula of binary molecular compounds

diphosphorus pentaoxide ______

trinitrogen heptabromide ______

Write the chemical formula of the following:

a)sulfur hexafluorideg) dinitrogen hexabromide

b)carbon dioxideh) sulfur dioxide

c)dinitrogen monoxidei) carbon monoxide

d)arsenic tribromidej) tetraphosphorous decaoxide

e)tetranitrogen hexahydridek) dinitrogen pentachloride

f) disulfur hexafluoridel) carbon tetrachloride

Write the proper chemical name of the following:

a)P2Cl5 g) SiS2

b)NCl3 h) OCl2

c)CS2 i) NO2(g)

d)ClBr2 j) P2O5

e)NO(g) k) SF6

f)N2O4 l) PBr5

Ionic compounds

Binary ionic compounds: No prefixes in naming.

3. Name the following binary ionic compound:

Atoms Involved / Ions Involved / Formula of Compound / Name of Compound
RbF
CdP
calcium oxide
gallium chloride
Li2Te(s)
InN(s)

4. Write the chemical formula of the following.

a)lithium hydrided) magnesium chloride

b)silver chloridee) aluminum hydride

c)sodium oxidef) barium sulfide

5. Write the proper chemical name of the following:

a)NaCl(s)d) ScCl3(s)

b)Al2S3(s)e) AlF3(s)

c)MgI2(s)f) LiBr(s)

Binary ionic compounds that contain a multi-valent positive ion:

Most transition metals and some representative metals can form more then one kind of ion. Since these metal elements have more than one valence or positive charge, they can therefore form more that one binary ionic compound.

6. Write the chemical formula of the following. Include the state.

a)chromium(II) oxided) vanadium(V) oxide

b)tin(II) iodidee) copper(I) bromide

c) copper(II) selenidef) lead(IV) oxide

7. Write the proper chemical name of the following:

a)MnCl4(s) d) SnCl4(s)

b)CuBr2(s) e) Hg2S(s)

c)FeO(s) f) Ni2S3(s)

Today:

p. 8 #1 p.9 #5 p.10 #6 p. 13 #7 p.23 #1

Test Tuesday

Polyatomic Ions

Some ions form groups called complex ions also known as polyatomic ions on your periodic table. The complex ions form bonds so strong they act as if they were single ions.

Like single ions, complex ions have a charge.

Consist of two or more different atoms containing an overall charge. e.g. NO31- nitrate ion

Found in the box at the top of the table.

-All are negatively charged, except ammoniumion, and most names end in ‘ate’

-All act as non-metals except ammonium ion, NH41+, which acts as a metal in compounds.

-Naming - same as ionic compounds.

-When writing formulas, bracketsmustsurround the polyatomic ion (when more than one is present – i.e. subscript is not 1).

Examples:

1. Potassium sulphate K1+(SO4)2- “trade”

charges

K2(SO4) or K2SO4

NH4NO3 Ammonium nitrate

Al(NO3)3 Aluminum nitrate

Sodium sulphateNa1+(SO4)2-Na2SO4

Na1+

SO42-

Na1+

Ammonium phosphate(NH4)1+(PO4)3-

(NH4)3PO4

Gallium hydrogen carbonate

Ga3+(HCO3)1-Ga(HCO3)3

Assignment: Write the formula or name the following:

magnesium sulphate
sodium phosphate
ammonium hydroxide
copper (II) nitrate
Ca(IO3)2
FeSO4
calcium sulphite
nickel (II) sulphate
copper (II) nitrate
copper (II) hydroxide
manganese (II) dichromate
sodium perchlorate
silver phosphate
cobalt (II) permanganate
Ca(OH)2

Some ions form groups called complex ions also known as polyatomic ions on your periodic table. The complex ions form bonds so strong they act as if they were single ions. Like single ions, complex ions have a charge.

There is only one positive complex ion: NH+, named ammonium. As it has a positive charge, ammonium will always be the first ion in an ionic compound.

All the other complex ions have negative charges. They will always come after the positive ion in an ionic compound. The names are given in your periodic table. Note that most of the negative complex ions contain oxygen as the last element. The names of these always end in either -ate or -ite.

There is one negative complex ion without the -ate/-ite name ending. It is OH- and is called hydroxide.

Formulas of compounds containing complex ions are written in and named in the same way as other ionic compounds.

The Mole

The mole is a number used in chemistry to indicate the number of atoms or molecules of a substance.

It is equal to6.02 x 1023.

This number is called Avogadro’s number.

(Similar to dozen)dozen = 12

mole = 6.02 x 1023

Atomic Molar Mass

-It is equal to the mass of 1 mol of all of the naturally occurring isotopes of the element

-listed for each element on the periodic table

-example 1 mol of iron = 55.85 g/mol

1 mol of zinc = 65.39 g/mol

-some elements exist as molecules such a nitrogen gas

1mol N2 = 2 x 14.01g/mol = 28.02g/mol

Molar Mass of a Compound(M)

- refers to the mass of 1 mol of any pure substance.

-to find the molar mass of a compound use the chemical formula

e.g.

CO2contains 1 carbon and 2 oxygen

1C = 1 x 12.01g/mol = 12.01

2 O = 2 x 16.00g/mol = 32.00

M = 44.01 g/mol

H2O2 x 1.01 = 2.02

1 x 16.00 = 16.00

M = 18.02 g/mol

Ca(OH)21 x 40.08 = 40.08

2 x 16.00 = 32.00

2 x 1.01 = 2.02

M = 74.10 g/mol

Assignment: Calculate the molar mass of the following compounds:

1. PbI2 2. NH4OH 3. CuSO4

4. CaPO4 5. Mn(NO3)56. Fe(OH)3

7. NH3 8. S2N49. BaSO4

10. C6H12O611. NH4HS 12. GaI3

13. CoCl214. Cobalt(III) silicate

15. Potassium phosphate

16. Polonium (II) oxide

17. Mercury (II) sulfide

18. Fe2(OOCCOO)3

19. Zn(OH)2

20.Cu(NO2)2

21.Co2(Cr2O7)322. MgHPO4

Calculating mass of a sample (m)

Molar mass (M) is equal to the mass of one mole of a compound.

For example the molar mass of water is 18.02 g/mol.

What if we have 2 moles of water?

Then the mass of the water would be 2 x 18.02 = 36.04 g.

We use the following formula:

m = nM

n = # of moles (mol)

m = mass (g)

M = molar mass (g/mol)

How many grams are there in 3.5 moles of francium nitride?

Step 1 – Write the formula and find the molar mass.

Fr3N

3 Fr – 3 x 223.00 = 669.00

1 N – 1 x 14.01 = 14.01

M = 683.01 g/mol

Step 2 – List what’s given and apply the formula.

n = 3.5 moles m = nM

M = 683.01 g/mol = (3.5)(683.01)

m = ?m = 2390.54 g

Mass of a substance to moles

If the mass of the sample is given rearrange the formula for “n” to find the number of moles.

n = m

e.g.

How many moles are there in a 16 g sample of carbon dioxide.

CO21 x 12.01 = 12.01

2 x 16.00 = 32.00

M = 44.01 g/mol

m = 16 g

M = 44.01 g/mol

n = ?n = m/M

= 16/44.01

n = 0.36 moles

Find the number of moles in 0.5 kg of water.

Note:you must change the mass of the sample to grams.

(kg to g x 1000)

m = 500 g

M = 18.02 g/mol

n = ?n = m/M

= 500

18.02

n = 27.75 mol

Moles summary

1. Molar mass (M) – must be calculated using the table.

2. Mass (m) – use the formula m = nM

3. Number of moles (n) – use n = m

M

Assignment: Find the number of moles in each sample.

1. 20 g of NH4OH

2. 1.3 kg of CaPO4

3. 670 g of S2N4

4. 0.450 kg of C6H12O6

5. 10 g CoCl2

6. 345 g Potassium phosphate

7. 700 g of Polonium (II) oxide

8. 0.9 kg of Mercury (II) sulfide

9. 200 g of Fe2(OOCCOO)3

10. 1.35 kg of Zn(OH)2

11. 320 g of Cu(NO2)2

12. 1,500 g of Co2(Cr2O7)3

13. 55 g of MgHPO4

14. 480 g of CuSO4

15. 980 g of Mn(NO3)5

16. 0.380 kg of Fe(OH)3

17. 2 kg of Mn(NO3)5

18. 280 g of Fe(OH)3

19. 1.3 kg of Water

20. 50 grams of table salt (Sodium chloride)