Chemical Bonding

Question 1

Chemical Bond

Answer 1

an attraction between atoms for electrons

Question 2

A chemical bond involves:

Answer 2

• attraction between nuclei for electrons
• electrons may be lost, gained, or shared when forming a bond
• the # of electrons in a chemical bond is such that each atom fills its valence shell
• 8 electrons fill the valence shell expect H and He only need 2

Question 3

When a bond is broken..

Answer 3

heat energy is absorbed and it’s an endothermic process

Question 4

When a bond is formed…

Answer 4

heat energy is released and it’s an exothermic process

Question 5

When energy is on left.. H2 + I2 + 53 KJ -> HI

Answer 5

more energy is absorbed to break bonds so it’s endothermic

Question 6

When energy is on right.. H2 + I2 -> H20 + 483.6 KJ

Answer 6

more energy is released in forming bonds so its exothermic

Question 7

Potential Energy

Answer 7

amount of energy stored within the bonds (distance between the atoms involved in the bond)

Question 8

When more energy is used to break bonds reaction is (endo) the potential energy

Answer 8

increases

Question 9

When more energy is used to form bonds reaction is (exo) the potential energy

Answer 9

decreases

Question 10

with endothermic the…

Answer 10

• potential energy increases
• breaking bonds
• less stable process
• easy to decompose

Question 11

with exothermic the…

Answer 11

• potential energy decreases
• forming bonds
• more stable process
• hard to decompose

Question 12

Ionic Bonds

Answer 12

form when metals transfer valence electrons to non-metals

Question 13

Ionic bonds are formed from the attraction between

Answer 13

positive and negative ions

Question 14

Ionic Substances are called

Answer 14

ionic compounds not molecules because molecules have neutral particles

Question 15

Ionic Bond Characteristics

Answer 15

• ionic bonds are very strong
• ions are held in a fixed position in a “crystal lattice structure.”
• ionic compounds are solids at room temp
• they have high melting points and high boiling points

Question 16

Ionic Compounds are

Answer 16

poor conductors as solids, good conductors when melted, good conductors when dissolved in water because ions are free to carry a current; soluble in polar solvents (ex. H2O)

Question 17

Ionic bonds form when

Answer 17

elements with large differences in electronegativity combine (difference 1.7 or greater ) - the stronger the ionic bond the greater the difference in EN

Question 18

ionic bonds have what type of diagram?

Answer 18

simple lewis dot diagram so like Br with it’s number of valency electrons or A metal with it;s ions and then a non metal with brackets.

Question 19

Covalent Bonds

Answer 19

involve the sharing of electrons between 2 non- metals - no ions are involved only molecules

Question 20

Properties of Covalent Bonds

Answer 20

A.K.A molecular substances (neutral)
most are poor conductors in all three phases of matter - including water (ex. Sugar) - low melting and boiling points
weak forced hold molecules together

Question 21

Non Polar Covalent Bonds

Answer 21

involve equal sharing of electrons (electrons spend same amount of time in the valence shell of both atoms )
form between 2 identical non-metals atoms - diatomics

Question 22

Polarity

Answer 22

refers to charge ; so non polar refers to no difference in charge - the electronegativity difference is always 0

Question 23

Allotropes

Answer 23

are different forms of an element - different physical properties due to different arrangement of atoms with different structure (diamond, graphite + oxygen and ozone)

Question 24

Polar covalent bonds

Answer 24

a bond in which atoms of 2 different non-metals share electrons unequally - electronegativity difference is between 0 and 1.7

Question 25

Ionic and Covalent bonds

Answer 25

compounds that are composed of both ionic and covalent bonds contain polyatomic ions

Question 26

Co-ordinate Covalent Bonds

Answer 26

AKA - free loader bonds: one atom supplies both electrons (lone pair) to be shared

Question 27

Network Bonds

Answer 27

consists of special covalently bonded atoms in a network; strong bonds; no separate particles; ultra high melting points; poor conductors; very hard substances

Question 28

what are the 4 examples of network bonds?

Answer 28

diamond, graphite, SiO2, and SiC

Question 29

Metallic Bonds

Answer 29

bonds that hold metal atoms together; very strong bonds, + nuclei in a ‘sea of mobile electrons” - free moving electrons give metals luster and conductivity - metals are good conductors in all 3 phases of matter

Question 30

Non polar molecules

Answer 30

have equal charge distribution and are symmetrical molecules

Question 31

types of shapes

Answer 31

linear, tetrahedral, bent, pyramidal

Question 32

Polar molecules

Answer 32

have unequal/uneven charge distribution and are not symmetrical

Question 33

SNAP

Answer 33

• Symmetrical - non polar molecule
  Asymmetrical - polar molecule