3.2- COVALENT BONDING

Question 1

What do non-metal atoms need to do to fill the space in their outer shells?

Answer 1

receive electrons

Question 2

What does a covalent bond form between?

Answer 2

a pair of non-metal atoms

Question 3

What do the atoms in a covalent bond do?

Answer 3

share some of their outer shell electrons

Question 4

Why do atoms in a covalent bond share some of their outer electrons?

Answer 4

so that each atom has a stable noble gas arrangement

Question 5

What is a covalent bond?

Answer 5

shared pair of electron

Question 6

What is a small group of covalently bonded atoms called?

Answer 6

a molecule

Question 7

example of a molecule from covalent bonding?

Answer 7

chlorine- Cl2

Question 8

How many electrons does chlorine have?

Answer 8

17

Question 9

What is the electron arrangement of chlorine?

Answer 9

1s2 2s2 2p6 3s2 3p5

Question 10

What happens when two chlorine atoms make a chlorine molecule? (4)

Answer 10

two atoms share one pair of electrons

each atom now has stable noble gas arrangement

formula is Cl2

molecules neutral as no electrons have been transferred from one atom to another

Question 11

How can you represent one pair of shared electrons in a covalent bond?

Answer 11

by a line

e.g. Cl-Cl

Question 12

How are atoms with covalent bonds held together?

Answer 12

by electrostatic attraction between nuclei and shared electrons

Question 13

How many electrons are there in a double bond?

Answer 13

four electrons

Question 14

How many pairs of electrons do the two atoms in an oxygen molecule share?

Answer 14

two

Question 15

What sort of bond is between the oxygen atoms in an oxygen molecule?

Answer 15

double bond

Question 16

How can you represent the two pairs of shared electrons in a covalent bond?

Answer 16

with a double line, O=O

Question 17

What sort of melting temperature do substances composed of molecules have?

Answer 17

low melting temperature

Question 18

Why do substances composed of molecules have a low melting temperature?

Answer 18

the strong covalent bonds only BETWEEN the atoms within a molecule
only weak attraction between molecules so molecules don’t need much energy to move apart from each other

Question 19

Are substances composed of molecules good conductors of electricity and why?

Answer 19

poor conductors of electricity as molecules neutral overall

Question 20

As the molecules are neutral overall what does this mean? (hint- current)

Answer 20

no charged particles to carry the current

Question 21

If substances composed of molecules were dissolved in water and remain as molecules, will they be able to conduct electricity and why?

Answer 21

no because there are no charged particles

Question 22

What does a single covalent bond consist of?

Answer 22

a pair of electrons shared between two atoms

Question 23

What is done by each atom in most covalent bonds?

Answer 23

each atom provides one of the electrons

Question 24

What happens in some bonds? (covalent)

Answer 24

one atom provides both the electrons

Question 25

What is it called when one atom provides both the electrons?

Answer 25

co-ordinate bonding or dative covalent bonding

Question 26

In co-ordinate/ dative covalent bond... (2)

Answer 26

atom that accepts electron pair is atom that doesn't have a filled outer main level of electrons- atom is electron-deficient atom that's donating electrons has a pair of electrons that's not being used in bond, called lone pair

Question 27

example of co-ordinate bonding?

Answer 27

ammonium ion NH4^+

Question 28

What does ammonia, NH3 have? (electrons)

Answer 28

lone pair of electrons

Question 29

What does nitrogen do in NH4^+?

Answer 29

nitrogen uses its lone pair of electrons to form coordinate bond with an H+ ion (bare proton with no electrons so electron deficient)

Question 30

How are coordinate covalent bonds represented?

Answer 30

by an arrow

Question 31

where does the arrow representing a coordinate covalent bond point towards?

Answer 31

towards the atom that's accepting the electron pair

Question 32

What does the arrow for coordinate bonding ONLY show?

Answer 32

only to show how the bonds was made

Question 33

about the ammonium ion:

Answer 33

completely symmetrical and all bonds have exactly the same strength + length

Question 34

What are the coordinate bonds' strength + length in comparison to ordinary covalent bonds?

Answer 34

exactly the same

Question 35

how is the ammonium ion bonded and does it have a charge?

Answer 35

covalently bonded but is a charged particle