unit 1

Question 1

what are the characteristics of the elements in the periodic table

Answer 1

• the atoms of the elements increase in mass as you go from left to right (starting with hydrigen) and downwards
• each element has an atomic number
• each element has a mass number

Question 2

what are atomic numbers

Answer 2

it tells you how many protons the element contains. the atomic number increases by one with every element

Question 3

what is a mass number

Answer 3

it tells you how many protons AND neutrons the element has in total

Question 4

protons, electrons, neutrons charge

Answer 4

protons = positive
electrons = negative
neutrons = no charge

Question 5

charge of an atom

Answer 5

an atom has no overall charge because the number of protons are the same as the number of electrons

Question 6

how can you work out the number of neutrons

Answer 6

minus the mass number by the atomic number

Question 7

who discovered the first model of the atom

Answer 7

J. J. Thompson and Ernest Rutherford

Question 8

who discovered the new model of the atom that is used today

Answer 8

the Danish scientist Niels Bohr, in 1913

Question 9

how are the electrons arranged

Answer 9

in electron shells around the nucleus

Question 10

what are holding the electrons in place

Answer 10

electrostatic forces

Question 11

the … shell has room for … electrons

Answer 11

first shell = 2 electrons
second and third shell = 8 electrons

Question 12

trends going down group 1

Answer 12

group 1 is also called alkali metals:
the reactivity of elements increases as you go down because
- the atoms become larger
- the outer electron becomes further away from the nucleus
- the force of attraction between nucleus and outer electron decreases
- outer electron is lost more easily

Question 13

(example) atomic structure of sodium (atomic number 11 mass number 23)

Answer 13

2, 8, 1

Question 14

inert meaning

Answer 14

unreactive

Question 15

all noble gases are…

Answer 15

inert/unreactive and do not form compounds

Question 16

how are atoms arranged

Answer 16

the electrons are arranged in different electron shells/energy levels around the nucleus. the shell with the highest energy level is called the outermost electron shell (the outside shell).

Question 17

why do elements react together

Answer 17

atoms are more stable when the outermost electron shell is completely full. groups 1 - 7 do not have full outer shells so they have to fill the outermost shell with electrons. 2 ways:
- atoms lose/gain electrons
- atoms share electrons

Question 18

losing electrons (sodium ex)

Answer 18

a sodium atom has 1 electron on its outershell. to make the atom stable, it must lose the electron on the outershell, leaving it with a full new outershell.
- when an atom loses an electron it becomes an ion
- when a sodium ion forms, the symbol is Na+ because it has one less electron than the atom, therefore it has one more positvely charged proton than negatively charged electrons

Question 19

gaining electrons (chlorine ex)

Answer 19

a chlorine atom has 7 electrons on its outershell, therefore it needs to gain one electron to make a full outershell and become stable.
- when it gains an electron, it becomes an ion.
- when a chlorine atom becomes an ion, the symbol changes from Cl to Cl-. this is because the atom now has one more negatively charged electron than positively charged protons