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Question

how do the physical and chemical properties of the elements change?

Answer 1

through physical and chemical reactions, respectively?

Answer 2

On inspecting the periodic table most elements are metals.
These metals are all in the solid state except mercury.
Metals in groups 1 & 2 are highly reaactive and not very dense.
Irrespective of Period as you go from group 1 to group 8(0) the elements become less metallic, first as metalloids(B), than as non-metals(C) and then as gases.(Ne).to site group 1.
The Transition metals (d-block) are heavy dense metals with high melting and boiling points, and slow to react.
Similarly the Lanthanide and Actinide Series are heavy dense metals with high melting and boiling points and slow to react..
The Inert gases are all unreactive and gases with low melting and boiling points.
Group 7 (Halogens) go from gas (F , Cl) to liquid (Br) to solid (I - nonmetallic)
Group 6 Go from gas (O), to non metals (S, Se,Te) , to metalloid (Po).
Group 5 Go from gas (N), to non metals(P, As), to metalloids (Sb, Bi).
Group 4 go from nonmetals (C, Si) to metalloids (Ge, Sn, Pb).
Group 3 go from nonmetals(B) to metalloids (Al, Ga,In,Tl).
Outside the Actinide Series there is only one Artificial element, it is Technetium (Tc) Atomic No. 43, Atomic Mass 98. It has all the properties of a 5th period transition metal, being dense and with a high melting(2200 degreesC) and a high boiling (3500 degrees C) points and is slow to react.