chem periodic table/trends in physical properties

Question 1

periodicity

Answer 1

1. elements in the same group have the same properties
2. the repeating pattern of physical and chemical properties shown by different periods is known as periodicity

Question 2

periodicity consequence

Answer 2

periodicity consequence

Question 3

what is the position of an element in the periodic table based on?

Answer 3

what is the position of an element in the periodic table based on?

Question 4

in base of what are the elements placed in the periodic table?

Answer 4

in base of what are the elements placed in the periodic table?

Question 5

what do e, p and n define?

Answer 5

e-chemical properties
p-identity
n-mass

Question 6

periods and groups

Answer 6

periods and groups

Question 7

metals non metals and metalloids

Answer 7

metals-metallic compound
non metals- covalent bonds
metalloids- they have the same numb of valence e as non metals (same chem prop) while they have similar phyisical prop as metals

Question 8

name of the separate group of elements below the periodic table

Answer 8

lanthanoids and actinoids

Question 9

exceptions in electron configuration

Answer 9

Cr has Ar 4s1 3d5 instead of 4s2 3d4
Cu has Ar 4s1 3d10 instead of 4s2 3d9

Question 10

nucleons

Answer 10

protons+neutrons

Question 11

half life

Answer 11

it means that it cannot be stable

Question 12

division of energy level

Answer 12

energy levels n=1
sublevels s p d f
orbitals 1 3 5 7

Question 13

Mn2+ electron configuration

Answer 13

remove 2 electrons
starting from the last energy level so 4s2 is before 3d10 for example (dram the triangle)

Question 14

noble gas electron conf of I

Answer 14

Kr 5s2 4d10 5p5

Question 15

atomic radius definition

Answer 15

the distance between the nucleus and the outermost e, but since we cannot predict the position of the e we can say that it is half the distance between the two nuclei of two bonded atoms of the same element

Question 16

atomic radius trends

Answer 16

increases down a group- because the energy levels increase which means that the outermost e get further away from the nucleus meaning that the distance increases

decreases across a period because electrons and protons are added so there is a stronger positive charge which causes the outermost electron to be more attracted to the nucleus (nuclear charge increases=attraction between outermost e and nucleus increases)

Question 17

ionic radius trends

Answer 17

increases down a group (with increase of neg charge)
decreases across a period (with increase of pos charge)

pos ions are smaller than their parent atom because to form a cation we are removing e from the outermost shell so the attraction between the outermost e and the nucleus increase resulting in a smaller size; so the increased attraction causes the e to move closer to the nucleus

neg ions are bigger then their parent atoms because to form anions we add e so the attraction between the outermost shell and the nucleus reduces; so there is an increase repulsion which causes the e to move further away

Question 18

what is important to consider when answering questions about ionic radius?

Answer 18

to mention how many occupied energy levels they have so defining the pull between the outermost e and the nucleus

Question 19

which molecules exist as diatomic molecules

Answer 19

N O F CL Br I H

Question 20

How to know which ionic radius is smaller when two ions have the same e and therefore the same conf.

Answer 20

we talk about protons and who has extra protons, you calculate this by subtracting the rounded relative atomic mass and the atomic number

Question 21

outer electrons

Answer 21

-involved in chemical reactions
-do not experience full nuclear charge (they are shielded from the nucleus)
-outer e of metals experience less effective nuclear charge the the ones of non metals

Question 22

simple general trends in the periodic table

Answer 22

down a group-increase in atomic size
across a period-increase in nuclear charge

Question 23

ionization energy definition

Answer 23

-measure of attraction between the nucleus and the outer e
it is the energy required to remove 1 mol of electron from 1 mol of gaseous atoms in their ground state (kjmol-1)
Ca(g) -> Ca+(g) + e-
Ca+(g) -> Ca2+(g) + e-

Question 24

ionization energies trends

Answer 24

increases across a period-increase in effective nuclear charge so the attraction between the outer e and the nucleus is stronger=more E is required to remove the outer e

decreases down a group-increase in atomic radius, so the increased dist between the nucleus and outer e is reduces the attraction so it requires less energy to remove the outer electron

Question 25

ionization energy exception 1

Answer 25

there is a large decrease between the last element of a period and the first of the next -because there is a rapid increase in atomic radius -because there is increased shielding by inner e both out weight the increased nuclear charge

Question 26

ionization energy exception 2

Answer 26

Be and B decreases Mg and Al decreases because it is easier to remove an e from the 2p orbital then from the 2s orbital

Question 27

ionization energy exception 3

Answer 27

N and O decreases P and S decreases because it is easier to remove paired electrons then unpaired electrons

Question 28

why is it easier to remove paired electrons

Answer 28

because when e pair up there is increased repulsion therefore it is easier to remove

Question 29

shielding

Answer 29

shielding is like putting layers between the nucleus and outer electrons, making the attraction a bit weaker. It helps explain why outer electrons might not feel the full force of the positive nucleus in an atom

Question 30

nuclear charge

Answer 30

positive charge in the nucleus due to the protons =atomic numb

Question 31

effective nuclear charge

Answer 31

net positive charge experienced by an electron in an atom, which is affected by the shielding effect from the inner e (it provides a more realistic measure of the attractive force experienced by outer electrons )

Question 32

difference between nuclear charge and effective nuclear charge

Answer 32

the first one only takes into consideration the positive charge of the nucleus without considering any electron shielding

Question 33

shielding trends

Answer 33

it increases down a group since the energy levels increase, and it decreases across a period since the nuclear charge increases

Question 34

which is larger the 2nd IE or the 1st?

Answer 34

the second it increases gradually, when there are big jumps it means that we are moving from one energy level to the next, when there are smaller shift it means that we are moving from one orbital to the other within the same energy level. it increases because when you remove an electron from a cation it is harder and requires more energy then removing it from an atom so therefore it increases every time

Question 35

equation for the 9th IE of Al

Answer 35

Al8+(g) -> Al9+(g) + e-

Question 36

IE graphs

Answer 36

from outer to inner e, the ones closest to zero are the outer e which are easier to remove, the first electrons indicate the valence e

Question 37

electronegativity

Answer 37

ability of its atoms to attract e in a covalent bond, it only applies to the consideration of covalent bonds

Question 38

electronegativity exceptions

Answer 38

noble gases do not have it since they already have a stable electron configuration

Question 39

electronegativity trends

Answer 39

same as ionization energy -decreases because the shared pair of e is further from the nucleus -increase because the shared pair is more strongly attracted

Question 40

electron affinity

Answer 40

energy change that occurs when an e is added to an isolated atom in the gaseous state energy change that occurs when one mole of e is added to one mole of gaseous atoms to form 1 mole of gaseous ions X(g) + e -> X-(g)

Question 41

exothermic

Answer 41

the process gives out energy since the e is attracted to the nucleus, the 1st is always exothermic, so negative

Question 42

electron affinity trends

Answer 42

down a group it becomes less exothermic (because less energy is realised when an e is brought into the outer most shell), across a period it become more exothermic

Question 43

electron affinity exceptions

Answer 43

oxygen, the first is exothermic while the 2nd is endothermic