Compounds & Bonds – Unit 5

Compounds & Bonds – Unit 5

Why do atoms bond to form compounds?

How are bonds formed?

How do we represent compounds (names and formulas)?

Bonding Essentials

Bonds are formed when valence electrons are gained, lost or shared by atoms

There are 3 major types of bonds Ionic, Covalent, Metallic

Compounds are 2 or more atoms bonded together, with different properties than their elements.

Chemical Bonding

I. Compounds: Definition:

Properties of compounds:

Compounds can be decomposed (separated) only by chemical means (not physical).

Chemical Bonds

Force between 2 atoms Three bond types:

________________________

________________________

________________________

Electronegativity

Ability of an atom in a compound to attract electrons from another atom.

Difference between electronegativity of atoms is used to determine the bond type.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

1H

2.1

2He

3Li

1.0

4Be1.5

5B

2.0

6C

2.5

7N

3.0

8O

3.5

9F

4.0

10Ne

11Na0.9

12Mg1.2

13Al1.5

14Si1.8

15P

2.1

16S

2.5

17Cl3.0

18Ar

19K

0.8

20Ca1.0

21Sc1.3

22Ti

1.5

23V

1.6

24Cr1.6

25Mn1.5

26Fe1.8

27Co1.9

28Ni1.9

29Cu1.9

30Zn1.6

31Ga1.6

32Ge1.8

33As2.0

34Se2.4

35Br2.8

36Kr3.0

37Rb0.8

38Sr1.0

39Y

1.2

40Zr1.4

41Nb1.6

42Mo1.8

43Tc1.9

44Ru2.2

45Rh2.2

46Pd2.2

47Ag1.9

48Cd1.7

49In

1.7

50Sn1.8

51Sb1.9

52Te2.1

53I

2.5

54Xe2.6

55Cs0.7

56Ba0.9

57La1.1

72Hf1.3

73Ta1.5

74W1.7

75Re1.9

76Os2.2

77Ir

2.2

78Pt2.2

79Au2.4

80Hg1.9

81Tl

1.8

82Pb1.9

83Bi1.9

84Po2.0

85At2.2

86Rn2.4

87Fr0.7

88Ra0.9

89Ac1.1

104Rf

105

Ha

106

Sg

107

Ns

108

Hs

109Mt

110

Uun

111Uuu

112Uub

Electronegativity Values for ElementsCircle elements with highest & lowest value & label.Show trends for EN using arrows.

Electronegativity Differences

Electronegativity Differences = ∆EN

O 3.2

Determining bond type

Determine the absolute

difference (either + or -)

Type?

O ___ - N____= _____

O ___ - O____=_____

O ___ - H____=_____

F____- Li ____=_____

Element EN

F 4.0 (4.1)

0 3.5

N 3.1

H 2.1

Li 1.0

Be 1.5

Electronegativity Learning Guide

Determine absolute differences Classify each bonding pair of elements as:

Ionic

Covalent If covalent, determine if the bond is:

non-polar (∆ 0 – 0.3) or

polar (∆0.4 – 1.7)

Ionic Bond∆EN = 1.8 – 3.2

Types of Bonds

Ionic

Covalent

Metallic

Ionic Bond

Ionic Bond: formed with

Bonds a __________ with a ____________

Valence electrons are ________________

from the ___________ to the __________.

Therefore, when the valence electron(s) are transferred to the ____-______, the NM become _______ charged (a ________).

Ionic bonds

The electronegativity difference must be equal to or greater than __________.

Ionic bonds look like:

Na Cl

Opposite charges attract= electrostatic attraction

Formula unit

Like the attraction of magnets

Ionic compounds

Ionic bonds form ionic compounds. An ionic compound is composed of positive (cations) and negative (anions) ions that are combined so that the negative and positive charges are equal.

Why do some atoms in formulas have subscripts and others do not?

Ionic Formula

Ionic formula units: The charges of the atoms in the compound must equal to zero.

Na ion (Na ) and Cl ion (Cl ) _______ + ________ = 0

Na ion (Na ) and Ca ion (Ca ) _______ + ________ = 0

Ionic compound names

Metal name + Non-metal (ide)

Prefix??

Note: will practice names & formulas after determining bonds

Opposites Attract

Find ions that can bond Write the symbol and the charge Write the new compound formed by

combining the ions. Name the compound. Write at least 15 compounds.

At least 10 should include subscripts.

Video: Discovery Ed

Ionic bonds

Covalent Bond

Non-metal and Non-metal

Sharing of electrons to form a bond

Covalent Bonds

Bonds a ___________ to a ___________.

Valence electrons are __________ between a _________ and a _________.

Electronegativity Difference

The electronegativity difference must be equal to or less than _______.

It is a polar covalent bond if the difference is between __________.

It is a non-polar covalent bond if the difference is between ___________.

Non-Polar Covalent Bond ∆EN= 0 – 0.3

The Electron pair that makes up the bond is shared evenly.

Non-Polar Covalent Bond

Polar Covalent Bond

Polar Covalent Bond∆EN = 0.4 – 1.7

The electron pair that makes up the bond is closer to the element that has the higher electronegativity.

Polar Covalent Bond

Covalent Bonds Covalent bonds form covalent compounds,

also called molecular compounds or molecules.Water Hydrogen

Polarity: unequal distribution of chargesOne side: more negative, The other side: more positive

Video: Discovery Ed – covalent bonds

Elements of chemistry: Compounds & Reactions

Metallic Bond

Metal to Metal

Electrons flow freely

Metallic Bonds

Bonds a _________ to a ____________. The valence electrons ________ ______

and are not bonded to one atom.

The valence electrons from a ______ of

________.

Metallic bond: Sea of electrons

The freedom of movement of the electrons in network of metals gives characteristic metallic properties:

-

-

-

Bond type

Compound(names & formulas)

Properties(physical and chemical)

Review

Metals __________ electrons because they have ________ electronegativity (EN)

Non-metals ________ electrons and have

________ electronegativity.

Warm-up: What type of bonds are created with:

Ionic, Covalent (non-polar or polar)

Use the PT (but not the electronegativity chart) Cr and Fe Rb and Br Cl and Cl H and F Ba and I S and S

Covalent Bonds – Strength

What is the Relationship between:- Bond energy & Bond length- Bond energy & Number of bonds

Intermolecular forces

What holds the separate covalent bonds together?

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Lewis structures:A different way

Practice Lewis structures (electron dot) Structural formula (shows bonds with lines) Introduce shape of compounds

VSEPR Determine polarity Identify diatomic molecules (7)

Electronic cereal:

Start with diatomic molecules 2 atoms of the same element (7)

Rules to follow: Make every compound

1. Use different colors for each atom

2. Show how each atom contributes electrons to the bond and the lone pairs

3. Determine shape & polarity 1. Polarity is?

Electronic Cereal: F₂

Working with Moles

Peer Tutoring: Working in pairs

Mole Flow Chart

Mole

Mole Conversions (Factor Label Method)

Moles ↔ GramsMolar mass: 1 mole of = ? Grams

Moles ↔ Particles (atoms, molecules, compounds, etc.)

1 mole = atoms

Review scientific notation

Moles ↔ Volume of Gas (at STP)1 mole of a gas = Liters

What I know: Show work

What I need to know:

Formula for conversion Answer with correct units:

Analyze the problem:




1. How many moles are in 100 Liters of Rn?




#4 How many atoms are in 3.5 moles of Xe?




#6 How many grams are in 3.75 moles of Kr?

Bond types determines properties of the compounds

Graphic organizer

Properties of Ionic Compounds

Structure: Crystalline solids (always)

Hardness Hard (like rocks)

Melting point: High

Boiling Point: High

Electrical Conductivity:

No : if solidYes: if melted or dissolved

Solubility in water:

Generally soluble

Properties of Covalent Compounds (molecules)

Structure Gas, Liquid or “soft” solid

Hardness Low Melting point Low to mediumBoiling Point Low to mediumElectrical conductivity NoSoluble in water Only if polar covalent

compound

Properties of Metallic Solids

Structure Solid

Hardness Medium (malleable, ductile)

Melting point Medium to high

Boiling point Medium to high

Electrical conductivity Yes

Soluble in water No

Ionic Bond

Ionic Compounds- Formulas

Opposites Attract

Find ions that can bond Write the symbol and the charge Write the new compound formed by

combining the ions. Name the compound. Write at least 15 compounds.

Ten should include subscripts.

Ionic CompoundsNames and Formulas

Binary

With Transition metals

With Polyatomic ions (Tertiary)

Transition metals can have more than one charge

Covalent CompoundsNames and Formulas

Review: Binary

Names & Formulas

Diatomic molecules

Acids

Bond type

Compound(names & formulas)

Properties(physical and chemical)

Foldable – Front cover Covalent Bonds

form Molecules

(Covalent compounds)

Ionic Bonds

form Ionic Compounds

Metallic Bonds

form Metallic Solids

Page 1

Covalent bond Picture

Ionic bond Picture

Metallic bond Picture

Type of atoms Electrons are: EN difference

Type of atoms Electrons are: EN difference

Type of atoms Electrons are:

Page 2

Molecules (covalent compounds) Lewis structure of water

Ionic Compounds (salts) Picture

Metallic solid

Properties of molecules

Properties of Ionic compounds

Properties of metallic solids

Page 3

Common examples of molecules

Common examples of ionic compounds

Common examples of metallic solids

Names & formulas- Binary molecules

- Binary ionic compounds

- Brass- Pewter- Sterling silver- Stainless steel

Page 4 – names & formulas

Molecules Diatomic molecules Acids

Ionic Compounds Transition metals Polyatomic ions

Metallic solids Bronze Gold

Lewis Diagrams Count and add the valence electrons for each atom. Put C as the central atom (or element with with

lowest electronegativity). Hydrogen is never the central atom

Place 2 electrons for each bond between 2 atoms. Arrange the other electrons evenly around the atoms

to satisfy the octet rule. Duet rule for H. If there are not enough electrons, make double or triple

bonds.

Lewis Diagrams

Valence Shell

Electron Pair Repulsion

VSEPR

This means:

Ionic Bond

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Compounds & Bonds – Unit 5