Chapter 4: Periodicity

Question 1

How are elements arranged in the Periodic Table?

Answer 1

By increasing atomic number.

Question 2

What do the vertical columns in the Periodic Table represent?

Answer 2

Groups.

Question 3

What do the rows in the Periodic Table represent?

Answer 3

Periods.

Question 4

What trend is observed in atomic radii across a period?

Answer 4

Atomic radii decrease.

Question 5

Why do atomic radii decrease across a period?

Answer 5

Increased nuclear charge pulls electrons closer.

Question 6

What trend is observed in atomic radii down a group?

Answer 6

Atomic radii increase.

Question 7

Why do atomic radii increase down a group?

Answer 7

More electron shells increase shielding.

Question 8

How does the size of positive ions compare to their parent atoms?

Answer 8

Positive ions are smaller.

Question 9

How does the size of negative ions compare to their parent atoms?

Answer 9

Negative ions are larger.

Question 10

What is the trend in ionic radii for positive ions from Groups 1 to 14?

Answer 10

Ionic radii decrease.

Question 11

What is the trend in ionic radii for negative ions from Groups 14 to 17?

Answer 11

Ionic radii decrease.

Question 12

Why do ionic radii decrease across a period?

Answer 12

Increased nuclear charge.

Question 13

What is the trend in ionic radii down a group?

Answer 13

Ionic radii increase.

Question 14

What is the general trend of ionization energy across a period?

Answer 14

Ionization energy increases.

Question 15

Why does ionization energy increase across a period?

Answer 15

Greater nuclear attraction makes electrons harder to remove.

Question 16

What is the general trend of ionization energy down a group?

Answer 16

Ionization energy decreases.

Question 17

Why does ionization energy decrease down a group?

Answer 17

Increased distance reduces nuclear attraction.

Question 18

What is electronegativity?

Answer 18

An atom’s ability to attract electrons in a covalent bond.

Question 19

What is the trend in electronegativity across a period?

Answer 19

Electronegativity increases.

Question 20

What is the trend in electronegativity down a group?

Answer 20

Electronegativity decreases.

Question 21

Which element has the highest electronegativity?

Answer 21

Fluorine (4.0).

Question 22

Which element has the lowest electronegativity?

Answer 22

Caesium (0.7).

Question 23

What happens to melting points down Group 1?

Answer 23

Melting points decrease.

Question 24

Why do melting points decrease down Group 1?

Answer 24

Decreased attraction between delocalized electrons and ions.

Question 25

What happens to melting points down Group 17?

Answer 25

Melting points increase.

Question 26

Why do melting points increase down Group 17?

Answer 26

Stronger London dispersion forces.

Question 27

What is the general trend in melting points across a period?

Answer 27

Increase to Group 14

Question 28

How does bonding change in Period 3?

Answer 28

Metallic → Giant covalent → Van der Waals forces.

Question 29

What ions do Group 1 elements form?

Answer 29

Single positive ions (M+).

Question 30

How do alkali metals react with water?

Answer 30

Form hydrogen and metal hydroxide.

Question 31

What ions do Group 17 elements form?

Answer 31

Single negative ions (M-).

Question 32

How do halogens react with Group 1 metals?

Answer 32

Form ionic halides.

Question 33

Why does chlorine displace bromide in reactions?

Answer 33

Chlorine has a stronger attraction for electrons.

Question 34

What type of molecules do halogens exist as?

Answer 34

Diatomic molecules (X2).

Question 35

What is the bonding nature of metallic oxides in Period 3?

Answer 35

Ionic and basic.

Question 36

What is the bonding nature of non-metallic oxides in Period 3?

Answer 36

Covalent and acidic.

Question 37

What are amphoteric oxides?

Answer 37

Oxides reacting with both acids and bases.

Question 38

Which Period 3 oxide shows amphoteric behavior?

Answer 38

Aluminium oxide.

Question 39

What holds Group 1 elements together in metallic structures?

Answer 39

Delocalized electrons and positive ions.

Question 40

What causes London dispersion forces to increase?

Answer 40

More electrons in a molecule.

Question 41

What trend occurs in metallic character across a period?

Answer 41

Decreases.

Question 42

What trend occurs in non-metallic character across a period?

Answer 42

Increases.

Question 43

Why do metallic structures have high melting points?

Answer 43

Strong metallic bonds.

Question 44

What determines bond type in covalent bonds?

Answer 44

Electronegativity difference.

Question 45

What type of bond forms if electronegativity difference is high?

Answer 45

Ionic bond.

Question 46

What type of bond forms if electronegativity difference is low?

Answer 46

Covalent bond.

Question 47

What group contains the most reactive metals?

Answer 47

Group 1.

Question 48

What group contains the most reactive non-metals?

Answer 48

Group 17.

Question 49

What happens to reactivity in Group 1 down the group?

Answer 49

Increases.

Question 50

What happens to reactivity in Group 17 down the group?

Answer 50

Decreases.

Question 51

What causes reactivity to increase in Group 1?

Answer 51

Easier electron loss.

Question 52

What causes reactivity to decrease in Group 17?

Answer 52

Harder electron gain.

Question 53

How does Group 1 store energy in reactions?

Answer 53

As exothermic heat.

Question 54

What happens to density down Group 1?

Answer 54

Density increases.

Question 55

What color are halogens in their elemental state?

Answer 55

Varies (e.g.

Question 56

What holds diatomic halogen molecules together?

Answer 56

Covalent bonds.

Question 57

What trend occurs in atomic mass across a period?

Answer 57

Atomic mass increases.

Question 58

How does electron shielding change down a group?

Answer 58

Increases.

Question 59

Why is shielding constant across a period?

Answer 59

Same principal quantum shell.

Question 60

What group does helium belong to?

Answer 60

Group 18 (Noble gases).

Question 61

What is a characteristic of noble gases?

Answer 61

Inert and unreactive.

Question 62

What phase are most Group 17 elements at room temperature?

Answer 62

Gases or liquids.

Question 63

What is the most abundant alkali metal?

Answer 63

Sodium (Na).

Question 64

What causes boiling points to increase in halogens?

Answer 64

Stronger intermolecular forces.

Question 65

What type of lattice does NaCl form?

Answer 65

Ionic lattice.

Question 66

Why does silicon have a high melting point?

Answer 66

Giant covalent structure.

Question 67

Why does argon have a low boiling point?

Answer 67

Weak van der Waals forces.

Question 68

What is the electron configuration of a sodium ion (Na+)?

Answer 68

1s² 2s² 2p⁶.

Question 69

What determines the strength of London dispersion forces?

Answer 69

Number of electrons.

Question 70

What defines Group 18 elements?

Answer 70

Full valence shell.

Question 71

How are period trends observed in electronegativity?

Answer 71

Left to right increase.

Question 72

What reaction product forms when halogens gain an electron?

Answer 72

Negative ions (X-).

Question 73

Why are alkali metals stored under oil?

Answer 73

To prevent reaction with air or water.