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:

1. Noble gases have full - valence shells, making them unreactive.
2. Alkali metals (metals) and halogens (non - metals) are highly reactive. Metals lose electrons and non - metals gain electrons to form compounds.
3. Elements in a row (period) have the same number of electron shells.
4. A valence electron is an electron in the outermost shell of an atom that participates in chemical bonding.
5. Elements in a group have similar chemical properties as they have the same number of valence electrons.
6. The number of valence electrons for groups 1 - 18 are 1, 2, 3, 4, 5, 6, 7, 8 respectively.
7. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond.
8. a) Atomic radii decrease across a period due to increasing nuclear charge. b) Atomic radii increase down a group due to addition of electron shells.
9. a) Ionization energy increases across a period due to increasing nuclear charge and decreasing atomic radius. b) Ionization energy decreases down a group due to increased atomic size and shielding effect.
10. a) Electronegativity increases across a period as the atom's ability to attract electrons increases. b) Electronegativity decreases down a group due to increased atomic size and shielding.

Answer:

1. Noble gases
2. Alkali metals (metals) and halogens (non - metals)
3. Same number of electron shells
4. An electron in the outermost shell of an atom that participates 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
9. a) Increase b) Decrease
10. a) Increase b) Decrease