Chapter 7

Compounds

Test corrections -done on a separate piece of paper -show your work (not just m/c letters!) -staple corrections sheet to your original test, and place in the hand-in bin :)

Lab Reports

• black or blue ink! • 1 mark: headings

– title, name, date, partner

– underlined with ruler

• 1 mark: purpose – in your own words

• 1 mark: procedure

• 4 marks: observations

– data table?

– graph?

• 5 marks: questions

– complete sentences

• 2 marks: conclusions

– Should include a discussion of results and errors

• 1 mark: neatness – no scribbles: single x-out

• Total: 15 marks

The Perfect Graph!

• Title • Labelled axes • Appropriate scale • Best fit line (do not

connect the dots) • Slope calculations • Correctly chosen

dependent/ independent variables

Displacement vs. time

Displacem

ent /m

Time /s

12

12

xx

yy

x

ym

−

−=

Δ

Δ=

Lab 6A Name Date Block Partner

Purpose: to separate elements from a compound Procedure: refer to text, p. 162-3 Observations:

Lab Prep

Procedure Step Observations

5

8

9

Design Lab Name Date Block Partner

Purpose: to see how density depends on salt added to water

Procedure: Step 1: measure 100 mL water Step 2: add 10 grams salt ... Observations:

Lab Prep

Procedure Step Observations

5

Questions:

1. Answer all questions in complete sentences

2. Challenges may be done for extra marks, but are not mandatory

Conclusions:

State the most important finding of the lab. List any sources of error and potential improvements you might make next time

Compounds are combinations of more than one elementThese always have a fixed ratio for a particular compound

Bohr Diagrams• We tend to see ions where atoms can give or

take a few electrons to get full outer, or “valence” shell

He

2p

2n

number of electrons

in outer shell = 2

Li

3p

4n

number of electrons

in outer shell = 1

Be

4p

5n

number of electrons

in outer shell = 2

Li

3p

4n

number of electrons

in outer shell = 1

Li

3p

4n

Lithium ion?

number of electrons

in outer shell = 0

F

9p

10n

Fluorine ion

number of electrons

in outer shell = 7

F

9p

10n

number of electrons

in outer shell = 8

Ex: write the formula then draw a Bohr model for nitrogen trichloride

Bohr Theory and Reactivity• All atoms want either a full, or empty

valence shell • Just one electron? Kick it out!

• All atoms want to be like a noble gas

Forming Ions• Atoms take the easiest route to get a full outer shell. Here are

examples:

Mg Mg

Atom Mg Ion Mg +2

It will lose 2 electrons to get a full outer shell.

F FAtom F (short 1 e- of a full shell)

Ion F-

The Rule!

• Losing electrons makes a positive ion.

• Gaining electrons makes it a negative ion.

Eg: Mn2+ Na+

Eg: I- O2-

Bohr Diagram of Ions

Bohr Model of N3- This minus means it has 3 extra electrons.

N-3 N3- 7

N-3

Bohr Model of Na+The plus means it’s missing an electron.

Na +

Na+ = only 10 electrons.

14

Try this:

Ion

15 P 1 e + 1 18 -

Net charge =

Symbol

Do Pg. 174 #s 1-6,10-12

Fill in the blanks.

Ionic vs Covalent compounds

Ionic Compounds

Formed from a metal and a non metal The metal gives up electrons The non metal takes electrons Tend to form rigid crystals

Covalent Compounds

Formed from non metals The non metals share electrons Tend to form molecules

Check your understanding

P. 182 q's 2-10 even numbers

Lab 6A conclusion

Summarize the most important discoveries or results of the lab. Any limitattons or possible improvements?

Ch 7 quiz 1

1. A 2. D 3. D 4. B 5. D 6. B SA1 element: only one kind of atom, can't be broken down chemically. Compound: more than one element SA2 hard, brittle crystals. High melting points, conduct electricity when dissolved in water

Chemical Formulae• Instead of writing out the whole name of a

compound, we can use symbols • e.g. sodium chloride: NaCl • calcium oxide: CaO

• Atoms of the same or different element can bind together in bunches called molecules. • e.g. molecule of an element:

• oxygen molecule: O2

• ozone molecule: O3

• molecule of a compound: • carbon dioxide: CO2

What do the numbers mean?• The subscript number to the RIGHT of

the symbol tells you how many of each there are: • ex: Aluminum oxide Al2O3 means:

• 2 aluminum for every 3 oxygen • What if there is no number?

• This means only one of this element

• ex: magnesium chloride MgCl2 means: • 2 chlorine for every one magnesium

• calcium oxide: CaO means: • one of each

Radicals

• These are groups of elements that behave like one atom • Also called “polyatomic ions”

• For example CaCO3 is called: • calcium carbonate • Notice we don’t change the name of the

radical in the chemical name

• Ex 2: Mg(OH)2 is: • magnesium hydroxide

How do we make a formula?

• Each element has its own ion charge • Ramses II had

over 100 children!!

Kris-Kross?

• The number of atoms of each element must be adjusted to find a common denominator • Criss-cross Applesauce! • Ex 1: hydrogen and oxygen

H1 O2

H2O1 or simply

H2O

• Ex 2: calcium and chlorine

Ca2 Cl1

Ca1Cl2 or simply

CaCl2• Ex 3: aluminum and oxygen

Al3 O2

Al2O3

Multiple personality disorder?

• Some elements have more than one possible combining capacity

• These will have Roman numerals in the name so you know which to use

• Ex 1: copper (I) oxide would be: • Cu1 O2

• Cu2O

• Ex 2: copper (II) oxide would be:

Cu2 O2 Cu2O2

CuO

• We still do criss-cross applesauce for radicals

• Ex 2: calcium and chlorite

Ca2 ClO21

Ca(ClO2)2

• Ex 3: aluminum and sulphate

Al3 SO42

Al2( SO4) 3

How do we name an ionic compound?

• Most compounds are a combination of a metal and non-metal (opposites attract)

• When we name a compound we write: • the name of the metal first, then • the name of the non-metal, with the ending of her

name changed to -ide • Ex 1: lithium + chlorine

→lithium chloride • Ex 2: calcium + fluorine

→calcium fluoride

Reverse Criss Cross?

• How do we know which CC we have? • Given the formula we can write the name.

• Ex: MnCl2

Mn2Cl1

• So the name would be:

• manganese(II)chloride

• Ex 3: Name Fe2O

3 • Think “reverse criss cross” • This iron must have a combining capacity of 3 • So this is iron (III) oxide

• Ex 4: Name FeO • This must be iron with a CC of 2 • So this is iron (II) oxide

Flowchart for naming compounds

Check your understanding

P. 191 q's 1-5 a-f only If finished, start vocab p. 196 choose 10

Naming molecular compounds

What's it called?

How do we know how many of each?We use prefixes to show the number:

What would you call...

Rules for naming:Make sure both elements are non metals Similar to naming ionic compounds, only change the second element's name to -ide Don't use mono- for the first element, e.g. CO is carbon monoxide, not monocarbon monoxide

CO₂ SO₃ N₂O₄

What would you call:

carbon dioxide sulfur trioxide dinitrogen tetraoxide

Check your understanding

P. 195 q's 1-3 a-f only

Review p. 198-190Also finish vocab p. 196 choose 10