Periodicity

Metals, nonmetals, & metalloids

Transition metals vs. representative elements

1

2

3

4 5

6

7

Groups of Elements Alkali Metals Alkaline Earth Metals Transition Metals Halogens Noble Gases

Trends in the periodic table

Groups (families) They all have the same # of outer electrons=

VALENCE ELECTRONS

Periods They have valence electrons in the same

highest energy level

Periodic trends Periodic = happens according to a repeating

pattern Periodic table has repeating pattern of

valence e- configurations Leads to periodic trends:

Atomic Radius Ion Formation and Ion size Ionization Energy Electronegativity

Periodic trend: Atomic Radius Size of atoms depends on:

Number of energy levels

Number of protons

Down a column: Across a row:

What is the trend across a period?Atomic Radii of Periods 1-3 of the Periodic Table

H

He

Li

Be

B

CN O F

Ne

Na

Al

SiP

SCl

Ar

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0.2

0 2 4 6 8 10 12 14 16 18 20

Atomic Number

Ato

mic

Ra

diu

s (

10-9

m)

A closer look at the trend across a period.Atomic Radii of Period 4 of the Periodic Table

0.1

0.12

0.14

0.16

0.18

0.2

0.22

0.24

16 21 26 31 36

Atomic Number

Ato

mic

Rad

ius

(10-9

m)

What is the trend down a group?

Atomic Radii of Group 2

Be

Mg

CaSr Ba

0

0.05

0.1

0.15

0.2

0.25

0 10 20 30 40 50 60

Atomic Number

Ato

mic

Rad

ius

(nm

)

Atomic radius increases down a group. The number of energy levels increases down a group Each subsequent energy level is further from the

nucleus .n=1

n=2

n=3

n=4

n=5

Atomic radius decreases across a row

Across a row valence electrons are in the same energy level (n=3)

Positive charge of nucleus is partially cancelled out by negative charge of core electrons =electron shielding

With each additional proton, there is a stronger force pulling the electrons closer to the nucleus. This results in a smaller atomic radius.

Electron shielding in Na vs. Cl

Shielding

Which has the greater atomic size, C or O?

Which has the greater atomic size, Li or K?

Ionization energy (kj/mol)

Recall emission lab…..

Ionization energy – the energy required to remove an electron from an atom. (pg. 358)

Ionization Energy- what is the trend?

Ionization Energy Periods 1-3

H

He

Li

BeB

C

NO

F

Ne

Na

MgAl

Si

SP

Cl

Al

0

500

1000

1500

2000

2500

0 2 4 6 8 10 12 14 16 18 20

Atomic Number

Ion

izatio

n E

nerg

y (kJ/m

ol)

Ionization Energy

Can you explain this trend? Click HERE for a tutorial.

Ionic Radii What happens to the size of the atomic radius

when an electron is removed?

Is an anion bigger or smaller than its neutral atom? Why?

Radii of neutral and charged atoms in pm (10-12m)

Purple models represent neutral atoms; Red=cations; Blue=anions

Check your understanding Which atom would be larger, and why?

N or O K or Rb Ne or Na

Which atom would be more difficult to turn into a cation (higher IE), and why? Li or Be Mg or Ca F or Ne

Electronegativity Electronegativity – is the ability of an atom to

ATTRACT electrons when the atom is in a compound. (pg 363)

Credit to Linus Pauling

Ionization & Ionic Compounds

Unit 3 • Chemistry 1 • Spring 2012

What’s an ion? Ion =

Cation Anion

Atoms form ions when they are able to give away or accept electrons.

The most likely type of ion an atom will form is based on the number of valence electrons it starts with.

Comparing cations and anionsCations Positive charge Valence e- removed Size vs. atom:

NaNa+

CuCu2+

Anions Negative charge Valence e- added Size vs. atom:

OO-

O2-

Ionization-how does it happen? How do ions form?

Will it be endothermic or exothermic?

What happens next?

Specific ions form for each element due to its electron configuration

Elements with electrons that completely fill the s and p orbitals of the highest energy level do not react.

Elements without “full” outer energy levels take, give up, or share electrons (chemical bonding).

Vocabulary: OCTET RULE ISOELECTRONIC

Cation formation How many valence electrons does Na have? Would Na give up its valence electron

spontaneously? Why does Na tend to form an Na+ cation,

rather than an Na2+ (or any other) cation?

What about Mg? What about F?

Anion formation How many valence electrons does F have? Is it possible to add an extra electron into the valence

energy level of F? Why does F tend to form an F- anion, rather than an

F2- (or any other) anion?

What about O? What about Be?

Electron configurations Write the electron configuration for each

neutral atom. What ion will form for each? F

O

Li

He

Ne

Cl

Symbols for ions: Use the chemical symbol and the charge for

each ion. Notice PT trends!

Some common ions

Periodic relationship of simple ions

Transition Metals?

Ionic bonding

Oppositely charged ions attract!

This forms a strong electrostatic attraction Called an Ionic Bond.

Atoms will become charged before making ionic bonds Ion

charged atom loss or gain of electrons

Cations: Anions:

(fulfills octet or duet rule)

Use periodic table to predict the ion formed for O, Li, He, Ne, and Cl

Ionic bonds-form a crystal lattice Ions form ionic crystals.

pattern of alternating + and – ions

An exothermic process.

Crystal structure extremely stable.

Click HERE for an animated tutorial

Ionic Solids

Salts are held together by ionic bonds

Ionic compounds When cations and anions come together to

form ionic bonds, an ionic compound is the result.

All compounds are neutral. Ex: Na reacts with S

Ionic Compounds Most ionic compounds are composed of a metal and

a nonmetal. Example: Sodium Chloride Example: Magnesium Oxide

Are ionic compounds charged?

Ionic compounds are NEUTRAL (no charge), so the two ions together must cancel each other’s charge. Example: Mg+2 and O-2 or Na+ and Cl-

One of each ion, makes a neutral ratio.

Ionic Compounds What if the ions are of different charges?

Example: Sodium and Oxygen Na+1 and O-2

The ions exist in ratios, producing an electrically neutral compound. 2 sodium ions for every oxygen ion

How can we write this as a formula? Na2O This formula shows NO charges, it is neutral There are two sodium ions for every oxygen It represents a RATIO of ions.

Practice writing formulas for the following ionic compounds:

potassium fluoride

calcium bromide

aluminum chloride

sodium sulfide

beryllium oxide

Formulas of ionic compounds potassium fluoride

KF calcium bromide

CaBr2

aluminum chloride AlCl3

sodium sulfide Na2S

beryllium oxide BeO

Rules for naming ionic compounds Salts (ionic compounds) are named:

Cation first, anion second. Cations are named the same as the neutral

atom, i.e. sodium, aluminum… they almost always end

in “-ium”. Anions are named with the ending “-ide”.

i.e. fluorine fluoride; oxygen oxide Examples: sodium chloride, magnesium oxide

Ions of transition metals Some transition metals can form more than one ion Roman numerals indicate which it is. Example:

Name: Nickel (I) oxide: Ions: Ni+1 and O-2

Formula: Ni2O

Example: Name: Cobalt (II) Chloride Ions: Co+2 and Cl-1

Formula: CoCl2

Roman numeral exceptions Some transition metals only form one stable ion and do

not require roman numerals: Ag+ Zn+2

A few other metals have more than one stable ion and require roman numerals: tin(II) and tin(IV) lead(II) and lead(IV)

Memorize these...

Practice writing names for ionic compounds of transition metals ZnCl2

PbBr2

AuO

Names of ionic compounds ZnCl2

zinc chloride

PbBr2

lead (II) bromide

AuO gold (II) oxide

Polyatomic ions: to memorizePolyatomic ion Name:

SO4

-2 sulfate

NO3-1 nitrate

CO3-2 carbonate

HCO3-1 bicarbonate

NH4+1 ammonium

OH-1 hydroxide PO4

-3 phosphate

CH3COO-1 (C2H3O2 -1) acetate

Formulas for ionic compounds: Iron(II) phosphate

Zinc carbonate

Aluminum nitride

Formulas for ionic compounds: Iron(II) phosphate Fe3(PO4)2

Zinc carbonate ZnCO3

Aluminum nitride AlN

Naming ionic compounds: MgSO4

Cu(OH)2

NH4Cl

Naming ionic compounds: MgSO4 magnesium sulfate

Cu(OH)2 copper(II) hydroxide

NH4Cl ammonium chloride

Introducing dimensional analysis. Suppose you work at a hardware

store and a customer comes in asking to buy 150 bolts from a bulk bin. What would be the most efficient way to get the customer his 150 bolts.

Counting large numbers

Atoms are too small to count one at a time!

The “mole” is a useful unit for counting atoms or other small particles.

1 mole = 6.022 x 1023 objects

Compare and contrast

Compare 5 dozen bagels to 5 dozen elephants How are they the same? How are they different?

Compare 2.5 moles of hydrogen atoms to 2.5 moles of gold atoms How are they the same? How are they different?

Avogadro’s Number

Ratio between grams and a.m.u.

Therefore, atomic masses on PT are also the molar masses of elements (in g/mol)

Counting by weighing We know the mass of 1 mole of any element

AND

We know how many atoms are in 1 mole of any element

THEREFORE we can “count” a certain number of atoms using mass.

Molar mass of compounds

To calculate the mass of one mole of a compound, add the molar masses of the atoms

EX: 1 mole of Al2O3 has 2 mol Al + 3 mol O

What is the molar mass of: Li3P NaOH Mg(NO3)2

Mole ratios for compounds

One mole of CaCl2 has mole(s) of Ca2+ ions mole(s) of Cl- ions

One mole of Al2(CO3)3 has mole(s) of Al3+ ions mole(s) of CO3

2- ions

Examples:

What is the mass of 1 mole of calcium atoms? What is the mass of 2 moles of calcium

atoms? What about 5.3 moles?

How many atoms are there in 2.25 moles of sulfur? What is the mass of this sample?

Conversion blueprint

Atoms (particles)

Moles Mass (g)

Calculations with ionic compounds

How many moles in 5000 kg of iron(III) oxide?

What is the mass of 2.50 mol of calcium chloride?

How many potassium ions are there in 4.5 moles of potassium oxide?

How many formula units are there in 285 g of copper(II) oxide?

Test Preparation: Start the review sheet…but don’t end there. Use practice problems from the book at the end of

the chapter. Power point DO PRACTICE PROBLEMS! Do the worksheets or

look over labs again. Be able to explain ideas completely. Cause and

effect.