Gr.11 T2 Chemistry

Question 1

What are valence electrons?

Answer 1

The number of electrons in the outermost energy level of an atom.

Question 2

What is electrostatic force?

Answer 2

The force of attraction or repulsion between two charged particles.

Question 3

What are chemical bonds?

Answer 3

The net electrostatic force that two atoms sharing electrons exert on each other.

Question 4

What is potential energy?

Answer 4

Energy due to the position of objects

Question 5

What is the main reason for atoms to bond?

Answer 5

Increased stability due to lower potential energy

Question 6

What is a dative covalent bond?

Answer 6

A bond where both electrons in the shared pair belong to the same atom.

Question 7

What is the VSEPR-theory?

Answer 7

Valence electron pairs will repel each other so that they are as far from each other as possible.

Question 8

Give examples of electron regions

Answer 8

Lone pair
Shared pair of electrons
Double/ triple bonds = 1 electron region
Etc.

Question 9

What is the shape of a molecule with 2 electron regions without lone pairs?
Also state the bond angle.

Answer 9

Linear

Bond angle = 180 degrees

Question 10

What is the shape of a molecule with 3 electron regions without lone pairs?
Also state the bond angle.

Answer 10

Trigonal planar

Bond angle = 120 degrees

Question 11

What is the shape of a molecule with 4 electron regions without lone pairs?
Also state the bond angle.

Answer 11

Tetrahedral

Bond angle = 109,5 degrees

Question 12

What is the shape of a molecule with 5 electron regions without lone pairs?
Also state the bond angle.

Answer 12

Trigonal bipyramidal

Bond angle = 120 degrees in trigonal plane and 90 degrees between plane and top and bottom atoms

Question 13

What is the shape of a molecule with 6 electron regions without lone pairs?
Also state the bond angle.

Answer 13

Octahedral

Bond angle = 90 degrees

Question 14

What is the shape of a molecule with 4 electron regions with 2 lone pairs?
Also state the bond angle. 💧

Answer 14

Angular

Bond angle = 104,5 degrees

Question 15

What is the shape of a molecule with 4 electron regions with 1 lone pair?
Also state the bond angle.

Answer 15

Trigonal pyramidal

Bond angle = 109 degrees

Question 16

What is electronegativity?

Answer 16

The tendency of an atom to attract electrons towards itself and form a negative ion.

Question 17

Below what point is a bond with a difference in EN a polar covalent bond?

Answer 17

< 2,1

Question 18

What will be zero if a molecule is non-polar?

Answer 18

The net dipole moment is 0

Question 19

What will be zero if a bond is non-polar?

Answer 19

The difference in electronegativity between the atoms

Question 20

What is another name for a non-polar molecule?

Answer 20

A symmetrical molecule

Question 21

What is a bond?

Answer 21

An electrostatic force of attraction holding atoms together.

Question 22

What is bond energy?

Answer 22

The energy needed to break a bond in a molecule when reagents are in the gas phase at standard conditions.

Question 23

What is bond length?

Answer 23

The average distance between the nuclei of two bonded atoms.

Question 24

What are forces between molecules called?

Answer 24

Intermolecular forces

Question 25

What are forces that hold atoms together inside a molecule called?

Answer 25

Intramolecular forces

Question 26

What are the 5 types of intermolecular forces?

Answer 26

``` Ion-dipole forces Ion-induced-dipole forces Dipole-dipole forces (some of which have hydrogen bonding) Dipole-induced-dipole forces London forces ```

Question 27

When are dipole-dipole forces hydrogen bonding?

Answer 27

When they are between a hydrogen atom covalently bonded to N,O or F and N,O or F of a neighbouring molecule.

Question 28

Why is hydrogen bonding so strong?

Answer 28

N,F,O have high electronegativity. Hydrogen atom left with no electrons (very positive). Therefore a very strong dipole. Valence electrons of N,F,O in second energy level (small atoms). Overall, molecules are small. Can get close to each other. Therefore a stronger dipole-dipole force.

Question 29

What is a melting point?

Answer 29

The temperature at which a solid becomes a liquid.

Question 30

What is the relationship between the molecular mass and the intermolecular forces of a substance?

Answer 30

Bigger molecular mass = stronger intermolecular forces

Question 31

What is the relationship between the density and the intermolecular forces of a substance?

Answer 31

Higher density = stronger intermolecular forces

Question 32

What is thermal expansion?

Answer 32

The ability of a substance to expand (increase in volume) with an increase in temperature

Question 33

What is thermal conductivity?

Answer 33

A material's ability to conduct heat energy.

Question 34

What is the relationship between thermal conductivity and the intermolecular forces of a substance?

Answer 34

Stronger IMF = better thermal conductivity

Question 35

Why do metals have high thermal conductivity?

Answer 35

Atoms are held together in a crystal lattice by strong electrostatic forces. Vibrations are passed on easily because particles are packed closely together.

Question 36

What is viscosity?

Answer 36

The resistance of a liquid to flow.

Question 37

What is the relationship between viscosity and the intermolecular forces of a substance?

Answer 37

Stronger IMF = more viscous liquid

Question 38

What are adhesion forces?

Answer 38

Forces between molecules of a substance and sides of the container.

Question 39

What are cohesion forces?

Answer 39

Forces between the molecules of a substance.

Question 40

Define specific heat capacity

Answer 40

The amount of heat required to raise the temperature of 1g of a substance with 1*C

Question 41

What do you call it when a liquid can flow in narrow spaces without assistance of external forces?

Answer 41

Capillary action

Question 42

What is molar mass?

Answer 42

The mass of one mol of a substance.

Question 43

How many kelvin is 0*C?

Answer 43

273K

Question 44

3 | What is 1 litre in dm ?

Answer 44

3 | 1 dm

Question 45

What is a bond angle? | Double-check with someone

Answer 45

The angle between atoms bonded to a central atom.

Question 46

What is 1 atm in Pa?

Answer 46

5 | 1 atm = 1,013 x 10 Pa

Question 47

Give the unit for each variable in the formula: V n = ----- Vm

Answer 47

n - mol 3 V / Vm (22,4) - dm

Question 48

What is the standard temperature and pressure (STP)?

Answer 48

Temperature: 0*C (273K) 5 Pressure: 1,013x10 Pa (1 atm)

Question 49

Give the unit for each variable in the formula: pV=nRT

Answer 49

``` p - Pa V - m3 n - mol R - gas constant (8,31) T - K ```

Question 50

What does a solution consist of?

Answer 50

Solute (solid) dissolved in a solvent (liquid) | ->homogeneous mixture

Question 51

What is molar concentration?

Answer 51

The amount of solute in moles per volume of solution.

Question 52

Give the unit for each variable in the formula: n c = ---- V

Answer 52

-3 c - mol.dm (molar concentration) n - mol V - dm3

Question 53

Give another version of this formula: n c = ---- V

Answer 53

m c = ------ MV

Question 54

What do square brackets show?

Answer 54

Concentration of the substance

Question 55

What is a standard solution?

Answer 55

A solution where the molar concentration is known precisely

Question 56

How is a standard solution made? | Make the solvent water for this example

Answer 56

Calculate how many grams of the solute you will need. Measure out that mass by putting small amounts of it into a watch glass on a scale until you reach that mass. Empty it through a funnel into a volumetric flask. Rinse the last bit from the watch glass and funnel using distilled water. Add a bit more distilled water and swirl the contents until the solute has dissolved. Fill the volumetric flask up to the line with distilled water.

Question 57

What is a limiting reactant?

Answer 57

The reactant that limits the amount of product formed.

Question 58

How do you calculate percentage yield?

Answer 58

Actual yield ----------------- x 100 Theoretical yield

Question 59

Give the formula for stomach acid

Answer 59

HCl

Question 60

What unit is used for actual/ theoretical yield?

Answer 60

g

Question 61

How do you calculate percentage purity?

Answer 61

mass of pure compound ------------------------- x100 mass of total sample

Question 62

What is a bond angle?

Answer 62

The angle between two atoms bonded to a central atom.

Question 63

What unit is sometimes replaced with by "M" (for molarity)?

Answer 63

- 3 mol. dm (The unit for molar concentration)

Question 64

When asked to give mole quantity or amount, answer is x mol. When asked to give the number of ions/ molecules etc., multiply mole quantity by Avogadro's number.

Answer 64

🌺

Question 65

Ionic bond

Answer 65

A chemical bond between a metal and a non-metal where electrons are transferred.