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

Are metals or non-metals brittle and dull?

Non-Metals

Are metals or non-metals good conductors of electricity and heat?

Metals

Are metals or non-metals poor conductors of electricity and heat?

Non-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

Do metals or non-metals have a lower melting and boiling points?

Non-metals

Do metals or non-metals lose electrons to form cations?

Metals

Do metals or non-metals gain electrons to form anions?

Non-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 (mercury)

Which non-metal is a liquid at room temperature?

Br (bromine)

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. Greater nuclear attraction causes the electrons to be pulled closer to the nucleus, reducing atomic size.

What is the trend for atomic radius going down a group?

Atomic radius increases due to the addition of electron shells.

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

Why does effective nuclear charge increase across a period?

The number of protons increase with no increase in electron shells, which leads to a greater attraction between the nucleus and valence electrons.

Why does effective nuclear charge increase going up a group?

The number of electron shells decreases, resulting in less shielding and a stronger attraction between the nucleus and valence electrons. The outer shell electrons become closer to the positively charged nucleus.

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

Do anions or cations have a larger radius?

Anions have a larger radius than cations due to the increase in electron-electron repulsion and added electrons.

Why do cations have a smaller radius?

Cations have a smaller radius due to the loss of electrons, which leads to a reduced electron-electron repulsion and a stronger attraction between the remaining electrons and the nucleus.

Do metals or non-metals form cations?

Metals typically form cations because they lose electrons easily, resulting in a positive charge due to the increased number of protons compared to electrons.

Do metals or non-metals form anions?

Non-metals typically form anions by gaining electrons, resulting in a negative charge due to the increased number of electrons compared to protons.

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 are the 2 exceptions to ionization energy?

Group 2 and Group 15 elements are more stable.

1. Group 2 (Alkaline earth metals) have filled orbitals (outer electron shell), resulting in higher ionization energy than Group 13 elements.

2. Group 15 elements (metalloids) exhibit a half-filled p subshell, resulting in higher ionization energy compared to Group 14 elements.

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, as the valence shell gets filled and increases nuclear charge, making it easier to add an electron.

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 are the 3 exceptions to electron affinity?

1. Noble gases have filled electron shells.

2. Group 2 (Alkaline earth metals) elements have filled s-orbitals resulting in very low electron affinity.

3. Group 15 elements have half-filled p-orbitals, their electron affinities are lower than group 14 of the same period.

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, as electrons are more strongly attracted by the nucleus as the atomic number (protons) increases.

Does electronegativity increase or decrease going down a group?

Decreases, as the atomic radius increases and more shielding is experienced, resulting in a weaker attraction to the nucleus.

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