Ions

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

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.

3 6.941+

Li

Lithium

- 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-metal non-metal

There are two basic types of compounds:1. Molecular2. Ionic

Molecular Compounds

Atoms which share electrons to become stable form molecular compounds

These groups of atoms are called moleculesAtoms in molecules are joined by covalent bonds.

All atoms in molecular compounds are non-metals.

Molecular compounds – 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

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

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

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

Prefixes:

1 = mono 6 = hexa2 = di 7 = hepta3 = tri 8 = octa MEMORIZE4 = tetra 9 = nona5 = penta 10 = 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:1. Silicon dioxide2. Sulphur monoxide3. OF2

4. SiBr4

5. PH3

6. N2O7. CO8. NBr3

9. P2I3

10. SO3 11. N2O4

12. Tetraphosphorous hexaoxide13. Dinitrogen tetraoxide14. Heptasilicon monobromide15. Octaboron decaiodide16. B2O3

17. BrF7

18. N3O6

19. H2Cl5

20. Triselenium diastatide21. Diarsenic pentaoxide22. Sulphur trioxide23. C3O2

24. C2H6

25. As3Br7

26. SO2

27. Selenium monoxide28. Diboron trioxide29. PF3

30. P2O5

31. P4O10

32. Arsenic trifluoride33. BrF7

34. Hydrogen chloride35. N2O36. 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

1. The first element in the name of the formula is the metal

2. The second element, the non-metal, is named as an ion. The suffix ‘ide’ must be present.

3. No prefixes are used.

e.g.

Fe2O3 – Iron oxideCuS – Copper sulfideKCl – Potassium chloride

Writing Formulas for Binary Ionic Compounds

In an ionic compound the total number of positive charges must equal the total negative charges – 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 isNaCl

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 oxide Cr3+O2-

Cr3+O2-to balance the charges we use a

shortcut method – charges are “traded” across.

Cr2O3

Calcium oxide Ca2+O2- Ca2O2 CaO

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) oxide Cu2+O2- CuO

Tin (IV) fluoride Sn4+F1- SnF4

PbI2 Lead (II) iodide

Pb2+ I1-

Cr2S3 Chromium (III) sulfide

Cr3+S2-

Is this formula correct LiO Li1+O2-

No – correct formula is Li2O

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

1.tin (II) fluride2.lead (IV) oxide3.iron (III) oxide4.iron (III) sulphide5.potassium chloride6.sodium oxide7.lead (II) oxide8.SbBr5

9.PbBr2

10. NaF11. sodium bromide12. iron (III) fluoride13. sodium chloride14. lithium nitride15. silver oxide16. magnesium bromide17. barium chloride18. potassium iodide19. zinc sulphide20. copper sulphide21. p. 11 #1

Review – Naming Molecular and Ionic Compounds Name ___________________

Binary molecular compound: Use prefixes for naming.

Write the formula of binary molecular compounds

diphosphorus pentaoxide _____________________

trinitrogen heptabromide _____________________

1. Write the chemical formula of the following:

a) sulfur hexafluoride g) dinitrogen hexabromide

b) carbon dioxide h) sulfur dioxide

c) dinitrogen monoxide i) carbon monoxide

d) arsenic tribromide j) tetraphosphorous decaoxide

e) tetranitrogen hexahydride k) dinitrogen pentachloride

f) disulfur hexafluoride l) carbon tetrachloride

2. 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

Rb F

Cd P

calcium oxide

gallium chloride

Li2Te(s)

InN(s)

4. Write the chemical formula of the following.

a) lithium hydride d) magnesium chloride

b) silver chloride e) aluminum hydride

c) sodium oxide f) 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) oxide d) vanadium(V) oxide

b) tin(II) iodide e) copper(I) bromide

c) copper(II) selenide f) 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. NO3

1- nitrate ion http://images.google.com/imgres?imgurl=http://www.iun.edu/~cpanhd/C101webnotes/chemical-nomenclature/images/polyions.jpg&imgrefurl=http://www.iun.edu/~cpanhd/C101webnotes/chemical-nomenclature/polyatomsalts.html&usg=__-WYRWKLq-pttehH2ZeF0dlC5-6Q=&h=360&w=429&sz=54&hl=en&start=3&um=1&itbs=1&tbnid=uTIoywSzo0c3DM:&tbnh=106&tbn

w=126&prev=/images%3Fq%3Dpolyatomic%2Btable%26hl%3Den%26rls%3Dcom.microsoft:en-US%26sa%3DX%26um%3D1

Found in the box at the top of the table.

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

- All act as non-metals except ammonium ion, NH4

1+, which acts as a metal in compounds.

- Naming - same as ionic compounds.- When writing formulas, brackets must

surround 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 sulphate Na1+(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:

1. magnesium sulphate2. sodium phosphate3. ammonium hydroxide4. copper (II) nitrate5. Ca(IO3)2

6. FeSO4

7. calcium sulphite8. nickel (II) sulphate9. copper (II) nitrate10. copper (II) hydroxide11. manganese (II) dichromate12. sodium perchlorate13. silver phosphate14. cobalt (II) permanganate15. 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 to 6.02 x 1023. This number is called Avogadro’s number.

(Similar to dozen) dozen = 12mole = 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. CO2 contains 1 carbon and 2 oxygen

1C = 1 x 12.01g/mol = 12.01

2 O = 2 x 16.00g/mol = 32.00M = 44.01 g/mol

H2O 2 x 1.01 = 2.021 x 16.00 = 16.00

M = 18.02 g/mol

Ca(OH)2 1 x 40.08 = 40.082 x 16.00 = 32.002 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)5 6. Fe(OH)3

7. NH3 8. S2N4 9. BaSO4

10. C6H12O6 11. NH4HS 12. GaI3

13. CoCl2 14. Cobalt(III) silicate15. Potassium phosphate16. Polonium (II) oxide17. Mercury (II) sulfide

18. Fe2(OOCCOO)3

19. Zn(OH)2

20.Cu(NO2)2

21.Co2(Cr2O7)3 22. 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 = nMn = # 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 = 669.001 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 = nMM = 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 M

e.g.

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

CO2 1 x 12.01 = 12.012 x 16.00 = 32.00

M = 44.01 g/mol

m = 16 gM = 44.01 g/moln = ? 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 gM = 18.02 g/moln = ? n = m/M

= 500

18.02n = 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 phosphate7. 700 g of Polonium (II) oxide8. 0.9 kg of Mercury (II) sulfide9. 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 Water20. 50 grams of table salt (Sodium chloride)