chemistry

Question 1

what is a chemical reaction?

Answer 1

intramolecular bonds in reactants are broken and new ones form the products

Question 2

how do you name an ionic chemical? (metal + non metal)

Answer 2

1. name element/group that comes first (metal)
2. a) if there’s only one other element, change the ending of it to ‘ide’
   b) if there are more than one, check the
   name for the polyatomic group

Question 3

how do you name covalent chemicals? (non-metal)

Answer 3

1. remove the ending of the 2nd element and add ‘ide’. Use the prefixes to show the number of atoms
2. if there’s only one atom in the first element you can drop its prefix
3. if there are two of the same vowels in a row, you can drop one

Question 4

law of conservation of mass

Answer 4

mass can neither be created nor destroyed, it can only be converted from one form to another

OR

in a chemical reaction the mass of the products is always equal to the mass of the reactants

Question 5

Identify the five factors that affect the rate of reaction

Answer 5

1. Increasing the concentration to
2. increase the number of reactant particles in the solution
3. Increase temperature of particle mixture
4. Increase the surface area by breaking up clumps into powders
5. Use a catalyst to lower activation energy
   Increasing the pressure

Question 6

what 3 things do particles need to do to collide? (collision theory)

Answer 6

1. collide with eachother
2. have enough energy (above Ea)
3. have correct orientation

Question 7

what is activation energy?

Answer 7

EA: minimum energy required for a reaction to take place

Question 8

list the prefixes for one to ten when naming chemicals

Answer 8

mono, di, tri, tetra, penta, hexa, hepta, octo, nona, deca

Question 9

what are isotopes? (list features)

Answer 9

3 different forms of an element
same number of protons
differing numbers of neutrons
differing atomic masses

Question 10

how do you represent elements in nuclide notation?

Answer 10

atomic mass on top, atomic number on bottom, element symbol next to them

Question 11

how do you represent elements in hyphenated form?

Answer 11

element name - atomic mass

Question 12

what are the three types of radiation?

Answer 12

alpha, beta gamma

Question 13

list the features of alpha radiation.

Answer 13

2 protons, 2 neutrons
useful for treating cancer
4 2 He or 4 2 (alpha)
low penetrating power: can be blocked by paper

Question 14

list the features of beta radiation

Answer 14

1. beta 2. positrons
   useful in medical imaging
2. 0 -1e 2. 0 +1 e
   medium pentrating power: can be blocked by aluminium

Question 15

list the features of gamma radiation

Answer 15

high energy electromagnetic radiation
x-rays, sterilisation, disenfection
happens after alpha or beta decay
0 0 y
high penetrating power: can be blocked by lead

Question 16

why do isotopes decay?

Answer 16

to become stable

Question 17

what happens if a particle has too many or too few neutrons?

Answer 17

the strong nuclear force is upset and the nucleus starts to decay until it reaches a more stable form

Question 18

what are half lives?

Answer 18

amount of time you would need to wait for half of the atoms in the radioisotope to decay into its daughter isotope

Question 19

what happens when atomic structures change?

Answer 19

the element changes, releasing energy. some mass is loss and converted into energy

Question 20

why are some elements radioactive but some are not

Answer 20

When the atoms of an element have extra neutrons or protons it creates extra energy in the nucleus and causes the atom to become unbalanced or unstable. An atom is stable if the forces among the particles that makeup the nucleus are balanced.

Question 21

why are some reactions fast and some slow?

Answer 21

If there are more molecules present, or there’s a bigger surface area on which the reaction happens, there will be more successful collisions and the reaction will go faster. Also, if the temperature is higher, more molecules will have enough energy to react, and the reaction will be faster.

collision theory!!