Periodic Properties

Question 1

What are valence electrons in terms of principal energy levels?

Answer 1

In main groups the VE are electrons in the outmost principal energy
level

In transition elements the VE are electrons in the outermost principal energy levels and the outermost d electrons

Question 2

What are core electrons in terms of principal energy levels?

Answer 2

complete principal energy levels and those in complete d and f sub-levels

Question 3

Where are the orbital blocks in the periodic table?

Answer 3

s block is groups 1+2 including helium

p block is groups 13-18 not including helium

d block is groups 3-12

f block is where the table splits

Question 4

What is different about chromium and copper’s electron configurations?

Answer 4

only put one electron in 4s orbital

4s^1 instead of 4s^2

Question 5

What groups lost/gain electrons to become stable ions?

Answer 5

Group 1 and 2 will lose 1 or 2 electrons to get a configuration like noble gas, aluminum loses 3 to become like noble gas

group 16 and 17 will gain 1 or 2 electrons to become like noble gas

Question 6

What is the trend for atomic size?

Answer 6

increases as you go down a column and decreases as you move from left to right across a row

Question 7

Why does atomic size increase as you go down a column?

Answer 7

the highest principal quantum number increases (n), valence electron occupy larger orbitals therefore larger atoms

Question 8

Why does atomic size decrease as you move across a row from left to right?

Answer 8

nuclear charge and the number of electrons increases but the value of n stays the same (larger Zeff)

Question 9

What is effective nuclear charge? What is the formula?

Answer 9

actual amount of attraction between nuclues and electrons

Zeff=z-s

(z is atomic number) (s is number of shielding electrons)

Question 10

What does a greater effective nuclear charge mean?

Answer 10

smaller atom size

Question 11

What is true about the atomic radius of transition metals?

Answer 11

The first two rows follow the same trend as the rest of the elements

stays roughly the same because the number of electrons in the outermost value of n stays the same so the increase in nuclear charge is balanced by an increased number of screening electrons

Question 12

What is the size of cations in relation to their normal atoms? Why?

Answer 12

they are much smaller than their corresponding atoms

because by decreasing the number of electrons while keeping the nuclear charge the same the attraction between the electrons and the nucleus increases, decreasing the size

Question 13

What is the size of anions in relation to their normal atoms? Why?

Answer 13

they are much larger than their corresponding atoms

because by increasing the number of electrons while keeping the nuclear charge the same the attraction between the electrons and the nucleus decreases, increasing the size

Question 14

What are isoelectronic species? What is affect on size?

Answer 14

All have the same number of electrons but different number of protons

At a fixed amount of electrons a greater nuclear charge results in a smaller atom or ion

Question 15

What is ionization energy?

Answer 15

Energy required to remove an electron from an atom or ion in the gaseous state

Question 16

What is relation between ionization energy and atomic radii? Why?

Answer 16

IE decreases as size increases

Further away means it needs less energy to remove (further away means lower IE)

Question 17

What is the difference between first and second ionization energies?

Answer 17

Energy required to remove first electron vs energy required to remove the second electron

IE2»>IE1

Question 18

What is the trends for first ionization energy?

Answer 18

Decreases going down a column because electrons are further away and held less tightly

Increases from left to right across a row because Zeff increases and therefore electrons are held tighter

Question 19

What are some exceptions to the trends in IE1?

Answer 19

Beryllium has a greater IE than Boron
- Because the ve in boron is in 2p and ve in beryllium is in 2s
- 2p had a higher energy than 2s so it’s easier to remove (s orbital penetrates)

Nitrogen has a higher IE than oxygen
- because the repulsion between the paired electrons in oxygens 2p orbital make it easier to remove them

Question 20

What is the trend for ionization energy for transition metals? Why?

Answer 20

IE increases across a row from left to right but the increase is smaller than main group elements

Third row has a higher IR than the first two rows

Charge of the nucleus increases
between rows but there is only a small increase in atomic size

Question 21

What is electron affinity?

Answer 21

energy released when an electron is added to a neutral atom in the gas phase

Question 22

What is the trend for electron affinity?

Answer 22

generally EA increases as we move from left to right across a row (not a strong trend)

Question 23

What is an exception in the trend for electron affinity? Why?

Answer 23

Group 15 has a smaller electron affinity than group 14

Group 15 has a valence shell ns^2np^3, when an electron is added the repulsion makes the EA to be smaller than group 14

Question 24

What are some properties of metals?

Answer 24

• good conductors of heat and electricity
• malleable and ductile
• high melting point
• tend to lose electrons

Question 25

What are some properties of non-metals?

Answer 25

• poor conductors of heat and electricity
• brittle
• low melting points
• tend to gain electrons

Question 26

What is the trend for metallic character? Why?

Answer 26

moving from left to right metallic character decreases (IE increases as we move to the right)

as we move down a column metallic character increases (IE decreases down a column)

Question 27

What are some characteristics of Alkali metals?

Answer 27

• group 1
• have ns^1 configurations
• atomic radius increases as you go down column
• IE decreases as you go down the column
• reactive with non-metals (halogens)

Question 28

What are some characteristics of alkaline earth metals?

Answer 28

• group 2
• have ns^2 configurations
• atomic radius increases as you go down column
• IE decreases as you go down column
• reactive with non-metals (halogens)

Question 29

What are some characteristics of halogens?

Answer 29

• group 17
• have ns^2np^5 configuration
• powerful oxidizing agents
• react with metals, hydrogen, and other halogens

Question 30

What are some characteristics of noble gases?

Answer 30

• group 18
• have ns^2np^6 configurations
• high IE makes them unreactive