Bonding and Calculations

Question 1

Compounds are _______ bonded

Answer 1

Compounds are chemically bonded

Question 2

What are isotopes?

Answer 2

Isotopes are different atomic forms of the same element.

DIFFERENT NUMBER OF NEUTRONS

Question 3

Ionic bonding is when…

Answer 3

Atoms transfer electrons to form positive and negatively charged ions

Question 4

Alkali metals react with group 7 by what form of bonding?

Answer 4

Ionic bonding

Question 5

Ionic compounds have what structure?

Answer 5

Giant ionic lattice

Question 6

What holds a giant ionic lattice structure together?

Answer 6

Very strong electrostatic forces of attraction between oppositely charged ions, in all directions

Question 7

What are some propitious of ionic compounds?

Answer 7

• High melting points/boiling points
  (Due to strong attractions)
• Dissolve easily in water

Question 8

Covalent bonding involves…

Answer 8

Covalent bonding involves sharing electrons

Question 9

Give some examples of covalent bonds

Answer 9

H2
Cl2
CH4 
HCl
NH3
H2O
O2

Question 10

Are the intermolecular forces between molecules in simple molecular substances string or weak?

Answer 10

Very weak

Question 11

How are the atoms bonded to each other in giant covalent structures?

Answer 11

Strong covalent bonds between ALL atoms

Question 12

Give some examples of giant covalent structures

Answer 12

Diamond
Graphite
Silicon Dioxide (silica)

Question 13

What are ‘free electrons’ also known as

Answer 13

Delocalised electrons

Question 14

How do the free or delocalised electrons help to hold the atoms together in metallic structures?

Answer 14

Strong electrostatic attraction between positive metal ions and the negative electrons

Question 15

What is the mass number of Carbon?

What is the atomic number of Carbon?

Answer 15

12

6

Question 16

Nitinol is a…

Answer 16

Shape memory alloy

Question 17

What can nitinol be used for?

Answer 17

Glasses frames

Dental braces

Question 18

What’re fullerenes? What’re they found in?

Answer 18

Fullerenes are molecules of carbon, shaped like hollow balls or closed tubes - arranged in hexagonal rings

They are found in nanoparticles

Question 19

What happens when you melt and cool thermosoftening polymers and why?

Answer 19

They’re easily melted, and when coiled, harden into the new shape

This is because they don’t have cross-lining between the chains of polymers

Question 20

What happens when you hear and cool thermosetting polymers and why?

Answer 20

The polymer doesn’t soften when heated - they’re strong, hard and rigid

This is because they have string intermolecular forces between polymer chains - called crosslinks

Question 21

What is Mr?

Answer 21

Relative formula mass

Question 22

What is Ar?

Answer 22

Relative atomic mass

Question 23

What is a mole?

Answer 23

The relative formula mass (Ar or Mr) of a substance in grams

Question 24

Number of moles =

Answer 24

 Mr (of substance)

Question 25

Nitinol is a...

Answer 25

Shape memory alloy

Question 26

What can nitinol be used for?

Answer 26

Glasses frames | Dental braces

Question 27

What're fullerenes? What're they found in?

Answer 27

Fullerenes are molecules of carbon, shaped like hollow balls or closed tubes - arranged in hexagonal rings They are found in nanoparticles

Question 28

What happens when you melt and cool thermosoftening polymers and why?

Answer 28

They're easily melted, and when coiled, harden into the new shape This is because they don't have cross-lining between the chains of polymers

Question 29

What happens when you hear and cool thermosetting polymers and why?

Answer 29

The polymer doesn't soften when heated - they're strong, hard and rigid This is because they have string intermolecular forces between polymer chains - called crosslinks

Question 30

What is Mr?

Answer 30

Relative formula mass

Question 31

What is Ar?

Answer 31

Relative atomic mass

Question 32

What is a mole?

Answer 32

The relative formula mass (Ar or Mr) of a substance in grams

Question 33

Number of moles =

Answer 33

Mass in g (of substance) ------------------------- Mr (of substance)

Question 34

Percentage mass of an element in a compound =

Answer 34

Ar x # of atoms ------------------------ Mr (of whole compound) x100

Question 35

How do you find the empirical formula

Answer 35

Experimental masses/Ar in its simplest ratio

Question 36

How do you calculate masses in reactions?

Answer 36

1) write out valences equation 2) work out Mr of the boys you want 3) find how much 1g makes, then multiply relatively to the question to find how much Xg makes

Question 37

Percentage yield =

Answer 37

``` Actual yield (grams) ------------------------ Predicted yield (grams) ``` x100

Question 38

Can a yield ever be 100%?

Answer 38

No