CHAPTERS 3.1-3.5

Question 1

what is a single covalent bond?

Answer 1

the covalent bond formed when atoms share two electrons, one from each atom.
eg. hydrogen (two hydrogen atoms share one electron to form a single covalent bond)

Question 2

what is a double covalent bond?

Answer 2

when two electrons are shared between atoms
eg. oxygen (each oxygen atom requires two electrons to gain a stable outer shell so when one oxygen bonds to another, each atoms shares two of its electrons)

Question 3

what is a triple covalent bond?

Answer 3

when three electron pairs are shared between two atoms.
eg. nitrogen (when a nitrogen atom bonds with another, each atom contributes three electrons to the bond that forms because nitrogen requires three electrons to gain a stable outer shell)

Question 4

what is a lewis structure (electron dot structure)?

Answer 4

it is a diagram used to represent molecules. it shows the valence shell electrons of an atom, as only these electrons are involved in bonding

Question 5

what are polyatomic molecules?

Answer 5

molecules made up of more than two atoms.
eg. water (H2O), methane (CH4), ethene (C2H4)

Question 6

what is the valence shell electron pair repulsion theory and what does it do?

Answer 6

it is a model used in chemistry to predict the shape of molecules. It states that electron pairs in the valence shell of an atom repel each other, causing them to arrange themselves to minimise this repulsion. by following this theory, chemists can determine the molecular geometry

Question 7

what is an example of a tetrahedral molecule?

Answer 7

methane (CH4)
electron groups: 4
lone pairs: 0

Question 8

what is an example of a pyrimidal molecule?

Answer 8

ammonia (NH3)
electron groups: 4
lone pairs: 2

Question 9

what is an example of a bent molecule?

Answer 9

water (H2O)
electron groups: 4
lone pairs: 4

Question 10

what is an example of a linear molecule?

Answer 10

hydrochloric acid (HCl)
electron groups: 4
lone pairs: 6

Question 11

what is a non polar bond? give an example.

Answer 11

bonds with an equal distribution of bonding electrons (no charge on either end of the bond)
eg. H2, O2, N2

Question 12

what is a polar bond? give an example

Answer 12

bonds with an imbalanced electron distribution
eg. CO2, HCN, PH3

Question 13

what is a dipole?

Answer 13

the separation into positive and negative charge as they have two oppositely charged poles at each end of the molecule

Question 14

how do you determine a covalent bond?

Answer 14

when the electronegativity difference between two atoms is zero (bond is also non polar)

Question 15

what happens to the polar nature of a bond between two atoms as the electronegativity between the atoms increases?

Answer 15

it increases.

Question 16

what are symmetrical molecules?

Answer 16

molecules that contain polar bonds that are evenly distributed. they are non polar, as the bond dipoles cancel each other out

Question 17

what are asymmetrical molecules?

Answer 17

molecules that contain polar bonds and are polar molecules. a net dipole is created in the molecule

Question 18

what is an example of a non polar molecule?

Answer 18

methane

Question 19

what is an example of a polar molecule?

Answer 19

chloromethane

Question 20

what are intermolecular forces?

Answer 20

forces of attraction or repulsion that act between neighbouring particles (atoms, molecules, or ions).

Question 21

what is a dispersion force?

Answer 21

forces that exist between all molecules, whether they are polar or non polar.

Question 22

what is a dipole dipole attraction?

Answer 22

it occurs between polar molecules. these forces result from the attraction between the positive and negative ends of the polar molecules

Question 23

what is hydrogen bonding?

Answer 23

a strong form of dipole dipole attraction. only occurs between highly polar molecules in which one of the molecules has a hydrogen atom covalently bonded to a nitrogen, oxygen or fluorine atom

Question 24

what is an allotrope?

Answer 24

the several different structural arrangements in the atoms of some elements. different forms of the same element