Atomic structure

Question 1

state the trend of atomic radius down a group and across a period

Answer 1

atomic radius decreases across a period and increases down the group

Question 2

explain why atomic radius decreases across a period

Answer 2

• atomic number increases therefore an increases positive nuclear charge
• the larger the nuclear charge the greater the pull of the nuclei on on the electrons which results in a smaller atom

Question 3

explian why atomic radius increases down the group

Answer 3

• there is an increased number of shells down the group
• the electrons in the inner shells repel the electrons in the outermost shell shielding them from the positive nuclear charge
• it weakens the pull of nuclei on the atom resulting in larger atoms

Question 4

define atomic radius

Answer 4

it is the measureof the size of an atom

Question 5

atomic radius has to do with…

Answer 5

atomic radius has to do with size of the atom and pull of nuclei on electrons
a greater/stronger pull means a smaller atom which means decreasing atomic radius
a weaker pull means a larger atom which means increasing atomic radius

Question 6

atomic radius is in/directly proportional to

Answer 6

-it is directly proportional to increase in number of shells

and indirectly proportional to increasig atmoic number/nuclear charge

Question 7

why is there a sharp increase in atomic radius from period to period (noble gas to alkali metal)

Answer 7

theres a an added principal quantum shell which increases the shielding of the outer shell electrons and therefore atomic radius

Question 8

define ionic radius`

Answer 8

measure of size of an ion

Question 9

state the predictable patterns of ionic radius`

Answer 9

ionic radius increases with increasing negative charge

and decreases with increasing positive charge

Question 10

what theory explains the patterns of ionic radius

Answer 10

the electron shell theory

Question 11

explain the increase in ionic radius with reference to the electron shell theory

Answer 11

ions with negative charges are formed by atoms that accept electrons (nuclear charge remains the same). the outer most electros are further away from the positively charged nucleus and are therefore held weakly by the attractive forces increasing the ionic radius

Question 12

eplain the decrease in ionic radius with reference to the electron shell theory

Answer 12

positively charged ions are formed by atoms that lose electrons (nuclear charge remains the same) however there are now fewer eectrons which undergo greater elctrostatic forces of attraction decreasing the ionic radius

Question 13

define an isotope

Answer 13

an isotope is an atom of the same element that contains the same number of protons but different number of neutrons

Question 14

why do isotopes have the same chemical energy

Answer 14

this due to isotopes having the same number of electrons in the outershells. electrons take part in chemical reactions and therefore determine the chemistry of an atom

Question 15

why do isottopes have diferent physical properties

Answer 15

the difference between isotopes is the number of neutrons and since these are natural subatomic particles they add mass to the atom resulting in different physical properties such as small differences in their mass and density