Question

periodic table of the elements
most elements (75%) are classified as
transition metals
properties: 1.
2.
3.
4.
5.
6.
7.
8.
9.
10.

Explanation:

1. For the first blank: In the periodic table, about 75% of elements are metals (including transition metals, alkali metals, alkaline earth metals, etc.). But the most common broad classification for the majority (and transition metals are a large group) - the first blank answer is "metals" (specifically, if focusing on the common major classification, most elements are metals, and transition metals are a major class of metals).
2. For transition metal properties:

• 1. Good conductors of heat and electricity (metallic property, transition metals have metallic bonding allowing electron flow).
• 2. High melting and boiling points (due to strong metallic bonding from delocalized electrons and close - packed structures).
• 3. Malleable and ductile (ability to be hammered into sheets or drawn into wires, from metallic bonding allowing layers to slide).
• 4. Form colored compounds (due to d - d electron transitions in partially filled d - orbitals).
• 5. Variable oxidation states (because of the availability of both s and d electrons for bonding, e.g., Fe has +2, +3).
• 6. Act as catalysts (many transition metals or their compounds, like Fe in Haber process, Pt in catalytic converters).
• 7. Have magnetic properties (due to unpaired electrons, e.g., Fe, Co, Ni are ferromagnetic).
• 8. Dense (high atomic masses and close - packed structures lead to high density).
• 9. Hard (except some like Hg, due to strong metallic bonding and atomic packing).
• 10. Form complex ions (ability to form coordination complexes with ligands, e.g., $[Cu(NH_3)_4]^{2+}$)

Answer:

• Most elements (75%) are classified as \boxed{metals} (specifically, a large portion are transition metals, but the general classification for the majority is metals).
• Transition Metals Properties:

1. \boxed{Good conductors of heat and electricity}
2. \boxed{High melting and boiling points}
3. \boxed{Malleable and ductile}
4. \boxed{Form colored compounds}
5. \boxed{Variable oxidation states}
6. \boxed{Act as catalysts}
7. \boxed{Have magnetic properties}
8. \boxed{Dense}
9. \boxed{Hard (usually)}
10. \boxed{Form complex ions}