Solutions to Alkali Metals

1.         The alkali metals are Li, Na, K, Rb, Cs, and Fr.

2.         They would soon react with oxygen and water in the air.

3.         (1)       they would react with oxygen

            (2)       they would react with water

            (3)       the metals are too soft

4.         halogens

5.         2 K + H₂ --> 2KH

6.         It is difficult to form Na⁺² ---2e) 7e) ----because it would disrupt the stable, noble-gas-like shell diagram of Na⁺¹. A better explanation: there was only one loose electron when sodium was neutral. But to form a +2 ion one would have to remove a second electron from a shell that is closer to the nucleus. Meanwhile there are still 11 protons pulling on those remaining 10 electrons.

7.         The alkali metals are Be, Mg, Ca, Sr, Ba and Ra.

8.         Alkali metals are softer and lower melting than alkaline earth metals.

9.         a.         +2

            b.         By losing their two valence electrons alkaline earth metal ions assume stable noble gas electron arrangements. Remember that the two valence electrons are loose since there are too mnay electrons in the way form the inner shells and not enough protons to pull in those valence electrons.

10.       ocean water, limestone, and bones

11.       CaO + H₂O --> Ca(OH)₂

12.       a.         Mg⁺³,

b.         Mg⁺³ is the most difficult to form because it would disrupt the stable, noble-gas-like shell diagram of Mg⁺². Mg⁺¹ is easier to form .Think of it as an in-between of neutral magnesium and Mg⁺².

Solutions to Halogens

1.         F, Cl, Br, I, At

2.         (1)       poor conductors of heat

            (2)       poor conductors of electricity

            (3)       include solids, liquids and gases at room temperature

3.         Halogens react with alkali metals, alkaline earths and hydrogen.

4.         I₂ + H₂ --> 2 HI

5.         halogens

6.         By acquiring one more electron, they get a noble gas-like electron arrangement. This configuration can also be achieved by sharing electrons, which is why they form diatomic molecules like F₂, Cl₂ etc.

7.         Heat the jars. Sodium will melt first.

8.         Neither is found in their neutral state. Each is reactive, desperate to lose either 1 or 2 electrons to get a noble gas-like electron arrangement.

9.         They could have reacted with the air in the half-empty container.

10.       Nothing

11.       Nothing. None of the noble gases burn.

12.       Fluorine because it is highly reactive. Xenon is far less reactive.

13.       a.         Be

            b.         Fr

            c.         Na

            d.         Ra

            e.         Mg

            f.          Cl

            g.         S

            h.         Ne

i.          He

            j.          I

            k.         Ca

            l.          B

            m.        N

            n.         Li

o.         Cl

            p.         F

            q.         Fr

            r.          Ar

s.         Ca

            t.          Br

            u.         Al

            v.         H

            w.        Fr

x.         N

            y.         B

            z.         Xe

aa.       Fr

bb.       Li or H

            cc.       Ra

dd.       Mg

ee.       He

ff.         Cl