Question

chemistry: exam 3 test review

1. what is the name of the group of elements that are the most unreactive and least likely to form a compound?
2. what is the name of the group of elements that are the most reactive and most likely to form a compound?
3. what do the elements in a row have in common?
4. what is the definition of a valence electron?
5. which elements have similar chemical properties? those in a group or in a period?
6. how many valence electrons does each of the following groups have? (hint: the number of valence electrons is equal to the atoms main group number)

1__ 2 13 14 15 16 17 18__

1. what is the definition of electronegativity?
2. what happens to the atomic radii?

a) as you go across the period:____
b) as you go down the group: ____
draw the arrows on the periodic table→

1. what happens to the ionization energy?

a) as you go across the period ____
b) as you go down the group ____
draw the arrows→

1. what happens to electronegativity?

a) as you go across the period ____
b) as you go down the group ____
draw the arrows→

Explanation:

Step1: Identify noble gases

Noble gases (Group 18) have full - valence shells, making them most unreactive.

Step2: Identify alkali metals and halogens

Alkali metals (Group 1) are most reactive metals and halogens (Group 17) are most reactive non - metals.

Step3: Analyze elements in a row

Elements in a row (period) have the same number of electron shells.

Step4: Define valence electron

A valence electron is an electron in the outermost shell of an atom, involved in chemical bonding.

Step5: Compare group and period

Elements in a group have similar chemical properties due to the same number of valence electrons.

Step6: Determine number of valence electrons

Group 1 has 1, Group 2 has 2, Group 13 has 3, Group 14 has 4, Group 15 has 5, Group 16 has 6, Group 17 has 7, Group 18 has 8 valence electrons.

Step7: Define electronegativity

Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.

Step8: Analyze atomic radii trends

a) As you go across a period, atomic radii decrease due to increased nuclear charge.
b) As you go down a group, atomic radii increase due to addition of electron shells.

Step9: Analyze ionization energy trends

a) As you go across a period, ionization energy increases due to increased nuclear charge and smaller atomic size.
b) As you go down a group, ionization energy decreases due to larger atomic size and increased shielding.

Step10: Analyze electronegativity trends

a) As you go across a period, electronegativity increases due to increased nuclear charge.
b) As you go down a group, electronegativity decreases due to larger atomic size and increased shielding.

Answer:

1. Noble gases
2. Alkali metals (metals) and halogens (non - metals)
3. The same number of electron shells
4. An electron in the outermost shell of an atom, involved in chemical bonding
5. Elements in a group
6. 1, 2, 3, 4, 5, 6, 7, 8
7. The ability of an atom to attract electrons towards itself in a chemical bond
8. a) Decrease

b) Increase

1. a) Increase

b) Decrease

1. a) Increase

b) Decrease