EL 4

Question 1

how did Mendeleev organise the periodic table

Answer 1

increasing atomic mass (protons + neutrons)
elements with similar properties were in the same vertical group
left gaps in the periodic table for elements that were not yet discovered

however atomic masses were not accurate since isotopes had not been discovered yet

Question 2

how is the modern periodic table organised

Answer 2

increasing atomic number (protons)
4 blocks labelled s, p, d, f
vertical columns- groups
horizontal rows- periods

Question 3

what is periodicity

Answer 3

periodic patterns

Question 4

what can you find out from a group on the periodic table

Answer 4

electrons in the outer shell
electrons lost or gained to make full outer shell
elements in same groups react similarly

Question 5

what can you find out from a period on the periodic table

Answer 5

amount of shells an element has
principle quantum number
estimate atomic radius (gets smaller along a period)

Question 6

what determines if an element has a high melting/boiling point

Answer 6

amount of energy taken to overcome intermolecular forces
larger the amount of energy taken = higher melting/boiling point

Question 7

how many electrons does each group loose or gain

Answer 7

group 1 looses - 1 (becomes +1)
group 2 looses - 2 (becomes +2)
group 6 gains - 2 (becomes 2-)
group 7 gains - 1 (becomes 1-)

Question 7

melting and boiling points of elements in period 3
Na- Ar

Answer 7

higher - H
lower - L

Na
Mg - H
Al - H
Si - H
P - L
S- H
Cl - L
Ar - L