Chapter 2 - Periodic Properties

In reference to the periodic table, what does a group refer to?

A group consists of elements that occupy the same column

What common characteristic do elements in a group share?

Same number of valence electrons

In reference to the periodic table, what does a period refer to?

A period consists of elements that occupy the same row

What common characteristic do elements in a period share?

Same number of electron shells

Which group of elements represents alkali metals?

Group 1

Which group of elements represents alkaline earth metals?

Group 2

Which group of elements represents noble gases?

Group 18

Which group of elements represents halogens?

Group 17

Which group(s) of elements represent transition metals?

Group 3-12

Which group of elements is most stable?

Elements found in group 18, the noble gases, are the most stable. The elements in this group have outer energy levels that are completely filled

Which group of metal elements is considered very reactive?

Group 1, alkali metals

Which group of non-metal elements is considered very reactive?

Group 17, halogens

Which period of elements represents the lanthanides?

Period 6

Which period of elements presents the actinides?

Period 7

Which element from Group 1 is not considered an alkali metal?

Hydrogen

How many elements exist as diatomic atoms?

7

What are the seven elements that exist as diatomic atoms?

Hydrogen, nitrogen, fluorine, oxygen, iodine, chlorine, and bromine

Are metals or non-metals malleable and lustrous?

Metals

Do metals or non-metals form basic oxides?

Metals

Do metals or non-metals form acidic oxides?

Non-metals

Do metals or non-metals have higher melting and boiling points?

Metals

Which physical state are most metals at room temperature?

Solid

Which physical state(s) are most non-metals at room temperature?

Gas or solid

Which metal is a liquid at room temperature?

Hg

Which non-metal is a liquid at room temperature?

Br

What is the trend for atomic radius as you move from left to right across the periodic table?

Radii decrease

Why does atomic radius decrease across a period?

Number of protons in an atom increases, resulting in greater nuclear attraction between the protons and electrons

What is the definition of effective nuclear charge?

The nuclear charge experienced by an electron in an atom with multiple electrons

What is the formula for calculating effective nuclear charge?

Effective nuclear charge = Z - S.

Z is # of protons; S is # of shielding electrons

What is the trend for effective nuclear charge in regards to the periodic table?

Increases across a period from left to right. Decreases going down a group

What is the definition of isoelectronic series?

Atoms and ions that have the same electron configuration, but differing numbers of protons. For example, O2-, F-, and Ne

What is the definition of ionization energy?

The energy needed to remove an electron from an atom

Is it possible for elements to have more than one ionization energy?

Yes

Are subsequent ionization energies typically smaller or larger than the first ionization energy?

Larger, because subsequent electrons are more difficult to remove

Does ionization energy increase or decrease going from left to right across the periodic table?

Increase, since there is an increase in effective nuclear charge

Does ionization energy increase or decrease going down a group on the periodic table?

Decrease, as shielding effect is increasing

What is the definition of electron affinity?

Amount of energy released when an electron is added to an atom

Does electron affinity increase or decrease going from left to right across a period?

Increases

Does electron affinity increase or decrease going down a group?

Decreases

Why does electron affinity decrease going down a group?

The attraction of an electron to the nucleus decreases due to shielding. Electron affinity, therefore, decreases

What is the definition of electronegativity?

Ability of an atom to attract electrons in a bond to itself

What does a high electronegativity imply?

The greater ability to attract an electron(s)

Does electronegativity increase or decrease going from left to right across a period?

Increases

What is the most electronegative element?

Fluorine

Which group of elements does not possess electronegativity?

Noble gases (group 18) as they have full valence shells and do not need additional electrons

Summary of periodic trends for review

Which of the row of transition metals is most likely to appear colorless? 

Row 4

Properties of transition metals

• High melting and boiling point 

• Good conductors of heat and electricity 

• Hard, tough, and has high density 

• Form colored-compounds (exception: row 4) 

• Multiple oxidation states

• Many are used as catalysts

Properties of non-metals

• Brittle

• Poor conductors of electricity/heat

• Form acidic oxides

• Gain electrons to form anions

• Gas or solid at room temperature, with the exceptions of bromine (which is a liquid)

• Generally, low melting and boiling points

Most transition metals readily form partially filled 

d-orbitals

The most prominent oxidation state for transition metals? 

+2

The most prominent oxidation state for inner transition metals? 

+3

Anions

• Gain electrons

• Larger radius

Cations

• Loss of electrons

• Smaller radius

Which elements have its valence electrons in the f-orbital.

an inner transition metal

Which elements have its valence electrons in the d-orbital.

Transition metals atoms

Inner transition metals are far less abundant on earth compared to…

transition metals

Why does the atomic radius increase right to left in a period

• Number protons decreases= Decrease in nuclear attraction

Why does the atomic radius increase down in a group

• Number of electron shells increase

Why does the effective nuclear charge increase left to right in a period

• Number protons increase with no inc in electron shells= Increase in nuclear attraction

Why does the effective nuclear charge increase up in a group

• Decrease in electron shells= outer electron shell pulled closer to positively charge nucleus

Why does the Ionization energy increase left to right in a period

• As valence shell fills, electrons become harder to remove to to increase in effective nuclear charge

Why does the ionization energy increase up in a group

• Fewer electron shells and less shielding from inner electrons makes it harder to remove valence electrons thus strengthening nuclear attraction to electron and thus requiring more energy

• Decreasing Atomic Size

Why does the electron affinity increase left to right in a period

• Across a period valence shell gets filled thus inc in attraction btwn nucleus and electron of atom

Why does the electron affinity increase up in a group

• Fewer electron shells, leading to decrease in electron shielding and inc in nuclear attraction to electrons

Why does the Electronegativity increase left to right in a period

• Ability of electron to attract electron pair increases

Why does the electronegativity increase up in a group

• Atomic radius decreases

• Valence electrons experience less shielding

• Ability to attract an e- pair increases

Exceptions for ionization energy

1. The first is that alkaline earth metals have filled orbitals, which gives them greater stability, leading to their higher ionization energy compared to Group 13 elements in the same period. This is why Be has higher ionization energy compared to B.

2. The second exception is that group 15 elements have half-filled orbitals, which gives it greater stability, leading to it higher ionization energy compared to Group 16 elements in the same period. This is why N has a higher ionization energy compared to O.

Exceptions for Electron affinity

1. The first is that group 2 elements have filled s-orbitals, so their electron affinities are very low

2. The second exception is that group 15 elements have half-filled orbitals p- orbitals, so their electron affinities are lower than group 14 elements of the same period

3. The third exception is that noble gases have filled electron shells, so their electron affinities are negligible