Answer
a) A transition metal - Cu.
(b) A nonmetal that forms a -3 ion – P.
(c) A noble gas – Kr.
(d) An alkali metal – Cs.
(e) A metal that forms a +3 ion – Al.
(f) A metalloid – Sb.
(g) An element that exists as a diatomic gas molecule – Cl.
(h) An alkaline earth metal – Sr.
Work Step by Step
a) A transition metal - Cu.
Copper is a metal in the fourth period and group 1B. It has 10 electrons in the 3d orbital and 1 electron in 4s (valence shell). An element is a transition element if it has the last electron in d orbital or in any of its stable oxidation state considered to be a transition element. And copper has +2 as its most common oxidation state with 9 electrons in the 3d orbital.
(b) A nonmetal that forms a -3 ion – P.
Phosphorus is a nonmetal in the third period and group 5A. It has 5 electrons in its valence shell and requires 3 more electrons to complete the octet. It has a tendency to accept 3 electrons and forms a -3 ion.
(c) A noble gas – Kr.
Krypton is gas in the fourth period and group 8A. It has 8 electrons in its valence shell. It has an octet configuration and is highly stable.
(d) An alkali metal – Cs.
Cesium is a metal in the sixth period and group 1A. It has only 1 electron in its valence shell and it has a tendency to lose 1 electron. It is highly electropositive in nature.
(e) A metal that forms a +3 ion – Al.
Aluminum is a metal in the third period and group 3A. It has 3 electrons in its valence shell and loses 3 electrons to complete the octet. Thus it forms a +3 ion.
(f) A metalloid – Sb.
Antimony is a brittle element with no structural uses in its pure form. Its electronic band structure is similar to a semimetal or a semiconductor.
It has ionization energy within the range of those of the metalloids.
(g) An element that exists as a diatomic gas molecule – Cl.
Chlorine is a nonmetal in the third period and group 7A. It has 7 electrons in its valence shell and requires 1 more electron to complete the octet. It has a tendency to accept 1 electron and so it forms a covalent bond with another chlorine atom. Hence Chlorine exists as a diatomic molecule.
(h) An alkaline earth metal – Sr.
Strontium is a metal in the fifth period and group 2A. It has 2 electrons in its valence shell. Its hydroxides are alkaline in nature.
