test 1

Question 1

what does the mass number equal to?

Answer 1

the total number of protons and neutrons in an atom

Question 2

what is an isotope?

Answer 2

an element with the same number of protons and a different number of neutrons

Question 3

how are isotopes similar/different?

Answer 3

same chemical properties, different physical properties (mass)

Question 4

how to calculate relative atomic mass?

Answer 4

(isotopic mass * % abundance) (isotopic mass * % abundance) / 100

Question 5

periodic table trend: ionisation energy

Answer 5

is the amount of energy required to remove the highest-energy electron
from a neutral atom.

increases across a period and up group because non-metals don’t want to lose electron

Question 6

periodic table trend: electronegativity

Answer 6

the ability to attract an electron. increases across period and up group. non-metals have a much higher ability to accept electrons.

Question 7

periodic table trend: atomic radius

Answer 7

increases going right to left from a period and going down. Fr being the biggest. it is the distance from the nucleus to the valence shell

Question 8

group number?

Answer 8

number of valence electrons

Question 9

period?

Answer 9

number of electron shells

Question 10

what happens when electrons are excited?

Answer 10

the valence electrons jump from ground state to excited state, when they return to ground state, they emit visible light.

Question 11

metallic bonding?

Answer 11

the bonding between two metals. it is a lattice of metal cations surrounded by a sea of delocalised electrons

Question 12

properties of metallic bonds?

Answer 12

• conductivity
  (due to mobile charged particles in electricity)
• malleability/ductile
  (can push the arrangement of the atoms across - will stay within structure due to delocalised electrons - when one layer moves, the ions are still held together by electrons)
• high m/b points (bond is very strong)
• lustrous (when ray of light hits electrons, becomes excited, releases light)

Question 13

how are metals reactive?

Answer 13

by shedding electrons, the easier they can lose the electron, the more reactive

Question 14

which metals react with acids?

Answer 14

all

Question 15

which metals react with water?

Answer 15

most 1, kind of group 2

Question 16

which metals react with oxygen?

Answer 16

1, 2 and some transition metals

Question 17

what is ionic bonding?

Answer 17

a bond between a non-metal and a metal. metal donates electron to non-metal. opposite charge makes them attract

Question 18

what shape is an ionic bond?

Answer 18

a three dimensional lattice with positively and negatively charged atoms held together by a strong electrostatic force

Question 19

properties of ionic bonds?

Answer 19

• high m/b points - attraction between bonds - lots of energy needed to break
• hard but brittle
  (molecules are different sizes, can’t slide, if they do they’ll break. if they slide, the same charge atoms will meet and repel, causing to break)
• not conductive in solid state (no mobile electrons) - conductive in solution or liquid (water interrupts bond - break apart and move around)

Question 20

properties of non-metals?

Answer 20

• low m/b points (inTERmolecular bonding in covalent bonds can be very weak)
  -not conductive (no delocalised electrons)

Question 21

intramolecular v intermolecular bonds?

Answer 21

intramolecular are the bonds between the atoms in the molecule, intermolecular are the forces amongst molecules. inTRAmolecular forces are very strong.

Question 22

what is a covalent bond?

Answer 22

share electrons between two non-metals, held together by their mutual attraction towards the electrons

Question 23

properties of covalent bonds?

Answer 23

• low m/b points (weak inTERmolecular forces)
• have an odour
• non-conductive (non mobile charged particles)
• insoluble in water, soluble in non-polar solvents (petrol)

Question 24

what is chemical energy?

Answer 24

chemical potential energy stored between the bonds

Question 25

what happens when bonds are formed?

Answer 25

energy is released, when it releases kinetic energy, they can form (exothermic)

Question 26

what happens when bonds are broken?

Answer 26

energy is absorbed, when it gains kinetic energy, they can break (endothermic)

Question 27

what is an exothermic reaction?

Answer 27

when energy is released from the system, the surroundings temperature increases. H(p) < H(r). H < 0. system cools down

Question 28

example of exothermic reaction

Answer 28

combustion

Question 29

what is an endothermic reaction?

Answer 29

energy is gained from the surroundings to the system. energy of products > reactants. H > 0. system heats up

Question 30

example of endothermic reaction

Answer 30

Decomposisiton

Question 31

what is activation energy?

Answer 31

referred to as an energy barrier that must be overcome for a reaction to proceed

Question 32

what requires more activation energy?

Answer 32

endothermic, which is why its slower

Question 33

what are nanoparticles? why are they used?

Answer 33

a small particle that ranges between 1-100 nm. large surface area to volume ratio, means there are more atoms on the surface compared to macro particles.

Question 34

disadvantage of nanoparticles?

Answer 34

can penetrate skin and enter bloodstream and cells - might interact with particles in body and cause unwanted chemical reaction. in sunscreen - long term health effects and affecting environment