Ch. 2: Periodic Table

Question 1

The original periodic table was arranged by atomic weight but the modern table is arranged by what?

Answer 1

Atomic number (# of protons)

Question 2

What is the difference between a period and group?

Answer 2

period = row
group = column

Question 3

What are common characteristics of metals at the atomic level?

Answer 3

Low effective nuclear charge
Low electronegativity
Large atomic radius
Small ionic raidus
Low ionization energy
Low electron affinity

Question 4

What are common physical characteristics of metals?

Answer 4

Malleability
Ductility
Good conductors
Luster

Question 5

What are common characteristics of NONmetals at the atomic level?

Answer 5

High ionization energies, electron affinities, and electronegativities. They also have small atomic radii and large ionic radii

Question 6

What are metalloids?

Answer 6

They share some properties with metals and other nonmetals. For instance, metalloids make good semiconductors due to their partial conductivity of electricity.

Question 7

What is effective nuclear charge (Zeff)?

Answer 7

The electrostatic ATTRACTION between valence shell electrons and the positive nucleus. The more positive the nucleus, the higher Zeff.

Question 8

What is the Zeff periodic trend?

Answer 8

Zeff increases from LEFT to RIGHT because protons increase as you go right.

Question 9

What happens to valence electrons as the principal quantum number increases?

Answer 9

Valence electrons become increasingly separated from the nucleus due to shielding by inner shell electrons

Question 10

Why does atomic radius decrease from left to right?

Answer 10

As you move left to right, protons are added to the nucleus and electrons are added to the outer shell, but the number of inner shell electrons stays the same. The increasing positivity of the nucleus pulls in the outer electrons decreasing the radius.

Question 11

How does atomic radius change in a group?

Answer 11

Atomic radius increases down a group.

Question 12

How does ionic radius change in a group and column?

Answer 12

Ionic radius DECREASES from LEFT to RIGHT.

Ionic radius INCREASES from top to bottom

Question 13

What is ionization energy?

Answer 13

The energy required to remove an electron from a gaseous species. This process is endothermic because it requires heat.

Question 14

What is the ionization energy periodic trend? Why?

Answer 14

The greater the atom’s Zeff or the closer the valence electrons are to the nucleus, the more tightly they are bound. This makes it more difficult to remove one or more electrons, increasing ionization energy. Thus, ionization energy increases from LEFT to RIGHT and from BOTTOM to TOP.

Question 15

Which group in the periodic table is least likely to give up electrons?

Answer 15

Group 18: noble gases – they have the highest ionization energies

Question 16

What is electron affinity?

Answer 16

The energy dissipated by a gaseous species when it gains an electron. This is an exothermic process.

Question 17

What is the electron affinity periodic trend? Why?

Answer 17

INCREASES from LEFT to RIGHT because the stronger the electrostatic pull between the nucleus and the valence shell electrons, the greater the energy release will be when the atom gains an electrons.

DECREASES from TOP to BOTTOM because the valence shell is farther way from the nucleus.

Question 18

What is the electronegativity periodic trend?

Answer 18

INCREASES from LEFT to RIGHT

INCREASES from BOTTOM to TOP

Question 19

Altogether, list the periodic trends of electronegativity, ionization energy, atomic radius, and electron affinity.

Answer 19

LEFT to RIGHT: ↑ electronegativity, ↑ ionization energy, ↑ electron affinity, ↓ atomic radius

BOTTOM to TOP: ↑ electronegativity, ↑ ionization energy, ↑ electron affinity, ↓ atomic radius

Question 20

What group represents the alkali metals? What are they?

Answer 20

Group 1
They have only one loosely bound electron in their outermost shell and have low Zeff. They are highly reactive with water and air.

Question 21

What group represents the alkali earth metals? What are they?

Answer 21

Group 2
They have two electrons in their valence shell. They are also very reactive and not found in their elemental form. Group 1 and 2 are considered active metals.

Question 22

What group represents the chalcogens?

Answer 22

Group 16

Question 23

What group represents the halogens? What are they?

Answer 23

Group 17

Highly reactive nonmetals with 7 valence electrons. They are desperate to gain an electron and complete their octet.

Question 24

What group represents the noble gases? What are they?

Answer 24

Group 18
These elements are inert because they have minimal chemical reactivity due to their filled valence shells. They have high ionization energies but little to no electronegativies.

Question 25

What groups represent the transition metals? What are they?

Answer 25

Group 3-12
They have low electron affinities, low ionization energies, and low electronegativies. But they have high melting points and boiling points, malleable, and good conductors. Many of them have many oxidation states.

Question 26

What are hydration complexes?

Answer 26

Complex ions tend to associate in solution with molecules of water. This changes the ions solubility and allows them absorb certain frequencies of light.

Question 27

How do we perceive color?

Answer 27

When we perceive a color, it’s because the color is NOT absorbed.