Bonding

Question 1

What are the three different types of bonding

Answer 1

Ionic bonding, metallic bonding and covalent bonding

Question 2

What are the characteristics of covalent bonds

Answer 2

• They mainly take place between of non-metals
• they form molecules
• atoms have a noble gas structure
• molecules are held together by the shared electron pair

Question 3

What are the characteristics of an ionic bond

Answer 3

-Metals transfer electrons to non metal
-positive and negative ions attract each other by electrostatic forces because they are oppositely charged
-the electrostatic Attraction is the ionic bond
-ionic bonds DO NOT form molecules
- they form a crystal lattice that is built up of alternate positive and negative ions

Question 4

What are the characteristics of metallic bonding

Answer 4

• the atoms of the metal have 1-3 valence electrons
• ionisation energy of a metal is low thus little energy is needed to delocalise
  -atoms in a metal are tightly packed together in an orderly crystal lattice

Question 5

Explain why metals glow by referring to metallic bonds

Answer 5

The sea of delocalised electrons can reflect light and therefore cause the surface to shine

Question 5

Explain why metals glow by referring to metallic bonds

Answer 5

The sea of delocalised electrons can reflect light and therefore cause the surface to shine

Question 6

Explain why metals are good conductors of electricity by referring to metallic bonds

Answer 6

The sea of delocalised electrons can move freely and act as charge carriers in the solid and liquid phase

Question 7

Explain why metals are good conductors of heat by referring to metallic bonds

Answer 7

The sea of delocalised electrons act as carriers of heat

Question 8

Explain how metals are shapeable by referring to metallic bonds

Answer 8

The atoms, although they are firmly bound together, can slide over one another, which allows metal to bend and stretch

Question 9

Explain How metals have a high density by referring to metallic bonds

Answer 9

The atoms of metals in the solid phase are packed closely together In a metal lattice

Question 10

How is steel formed

Answer 10

With iron and carbon

Question 11

How is stainless steel formed

Answer 11

Iron, chromium, nickel

Question 12

How is bronze formed

Answer 12

Copper and tin

Question 13

What are molecular shapes

Answer 13

The special three dimensional arrangement of atoms in a molecule

Question 14

What properties does the shape of a molecule influence

Answer 14

Boiling point, melting point, density and the type of chemical reactions it will undergo

Question 15

How do we predict the geometric shape of molecules formed through non-metal atoms

Answer 15

Valence Shell electron pair repulsion model (VSEPR model)

Question 16

What idea is the VSEPR model based on

Answer 16

The idea that structural electron pairs repel each other as far as possible in space. This ensures the lowest possible potential energy, which as a result makes it more stable. The positions they take up determine the angles between the bonded atoms in a molecule

Question 17

What are the two types of geometry the VSEPR model works with

Answer 17

Electron pair geometry and molecular geometry

Question 18

What are the five ideal molecular shapes

Answer 18

Linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral

Question 19

What is the bond angle for a linear molecule

Answer 19

180 degrees

Question 20

What is the bond angle for a trigonal planar molecule

Answer 20

120 degrees

Question 21

What is the bond angle in a tetrahedral molecule

Answer 21

109,5 degrees

Question 22

What is the bond angle in a trigonal bipyramidal molecule

Answer 22

120 degrees and 90 degrees

Question 23

What is the bond angle in an octahedral molecule

Answer 23

90 degrees

Question 24

Explain the formation of non ideal molecules

Answer 24

- lone pairs are slightly bigger and repel each other and other bond electrons more, so the bonding angle closes slightly. - there are three type of repulsion forces (LP-LP, LP-BP, BP-BP) whose repulsion is in order of biggest to smallest - however if the number of atoms is equal to the number of electron pairs it will keep the ideal molecular shape.

Question 25

What are the two types of non-ideal shapes

Answer 25

Angular and trigonal pyramidal

Question 26

What is the bond angle for trigonal pyramidal molecules

Answer 26

107 degrees

Question 27

What is the bond angle for angular molecules

Answer 27

104,5 degrees

Question 28

How do you format summary answer of bond angles

Answer 28

- talk about number electron pairs (a double bond is treated as a single bond with one bonding pair) - talk about electron pair geometry shape - talk about number of atoms around central atom - talk about molecular geometry shape - talk about bond angle (refer to specific angle eg. N-H-N is 107 degrees) and if there is lone pairs talk about how angle is now slightly smaller than ideal shape.

Question 29

What does electronegativity depend on

Answer 29

Electron structure: the tendency to release or obtain electrons to form the octet structure. Non metals have higher electronegativity than this of metals Atomic radius: the closer the valence electrons are to the nucleus the tighter it holds on to it Energy levels: the more energy levels there are the more electrons there are shielding the nucleus from holding on more tightly to the valence electrons

Question 30

What is bond length

Answer 30

The average distance between the nuclei of two atoms in a molecule

Question 31

What Influences the bond length of bonded atoms

Answer 31

Atom size, electronegativity, and bond order

Question 32

How does the size of the atom influence the bond length

Answer 32

The bond length increases as the size of the atom increases. Thus weakening the bond strength

Question 33

How does electronegativity influence bond length

Answer 33

The greater the difference in electronegativity will lead to a shorter bond length and thus a stronger bond

Question 34

What is bond order

Answer 34

Bond order is the number of bonds (single, double, triple) which exists between two atoms

Question 35

How does bond order influence bond length

Answer 35

The higher the bond order the shorter the bond length and the stronger the bond

Question 36

What is bond energy

Answer 36

The energy necessary to break one mol of a specific covalent bond in the gaseous phase

Question 37

What does positive (+) energy represent

Answer 37

Energy is absorbed

Question 38

What does negative (-) energy represent

Answer 38

Energy is released

Question 39

What is the relationship between bond length and bond energy

Answer 39

Inverse relationship. The stronger the bond the shorter the bond length and the weaker the bond the longer the bond length

Question 40

What are the factors that influence bond energy

Answer 40

Bond length Bond energy Size of the atom Bond order