Periodic Table Trends

Atoms with 1 valence electron

Alkali metals

Largest atomic radius + least dense in their period

Alkali metals

Most reactive elements

Alkali metals

Atoms have 2 valence electrons

Alkaline Earth Metals

What trend in atomic radius do you see as you move across a period on the periodic table? Why? (use Coulomb's law)

As you go across a period on the periodic table, the atomic radius decreases. This happens because the attraction the nucleus has on it's surrounding electrons increases as a result of additional protons. With a stronger nucleus, atoms on any given energy level will have a greater pull on surrounding electrons in comparison to elements on the same period with less protons. A stronger nucleus packs pulls electrons closer, packing them more tightly together and, ultimately, decreasing the atomic radius.

What trend in ionization energy do you see as you go across a period on the periodic table? Why? (use Coulomb's law)

As you go across a period on the periodic table, the ionization energy increases. Because the number of protons increases as you go across a period, and an increased number of protons raises the attraction of the nucleus, electrons become more attracted to nuclei. This increased attraction makes it more difficult to remove an electron from the atom's outermost shell, which is, by definition, ionization energy.

What trend in ionization energy do you see as you go down a family on the periodic table? (use Coulomb's law)

As you go down a family on the periodic table, ionization energy decreases. The number of energy levels increases as you go down the periodic table. In any given family, an atom with more electron shells than an atom with less will have less of a grip on it's electrons because both nuclei have relatively the same attraction. Increased energy levels cause the nucleus to have less of a pull on it's furthermost electrons, making it easier to remove one electron from it's outermost shell. By definition, ionization energy is the amount of energy it takes to remove one electron from an atom's electron shell, therefore the ionization energy decreases as you go down a group on the periodic table.

What trend in atomic radius do you see as you move down a family on the periodic table? Why? (use Coulomb's law)

As you move down a family on the periodic table, the atomic radius increases. This happens because the number of energy levels increases as you go down a family on the period table, and increased electron shells around an atom with a barely increasing attraction (energy levels make a much more noticeable difference on the radius than additional protons do), will lessen the nucleus's pull on the electrons in it's shell. The electrons, with a lessened attraction to the nucleus, will spread, increasing the distance between them-the atomic radius.

Liquids at room temperature

Bromine (Br), Mercury (Hg)

Alkaline Earth Metals

Extremely high melting/boiling points two valence electrons, group 2 on the periodic table.

Most reactive nonmetals

Halogens

Properties of Metals?

Malleable, ductile, lustrous, oxidize easily, good conductors of heat and energy; encompass alkali metals, alkaline earth metals, and transition metals.

Halogens

Most reactive nonmetals, very high electronegativities, highly reactive with alkali and alkaline earth metals, always exist as diatomic molecules in their elemental form, group 17 on periodic table.

Alkali Metals

Most reactive, largest atomic radius/least dense in their period, one valence electron, silvery/gold in color, not found in nature, group 1 on the periodic table.

Transition Metals

Most useful metals, forms colorful compounds, this family contains gases/liquids/solids, high melting/boiling points (except Mercury), have unpaired electrons so they can refract light, group 3-12 on periodic table.

Unreactive elements

Noble gases

Gases at room temperature

Noble gases + Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine

Forms colorful compounds

Transition Metals

High melting and boiling points (except mercury)

Transition metals

Most useful metals

Transition metals

Noble Gases

Unreactive (or barely reactive) elements, all gases at room temperature, complete electron shell so very stable, low boiling points, group 18 on periodic table

Nonmetals

brittle solids, easily gain electrons, not good conductors of heat or energy, encompass halogens and noble gases.

Metalloids

elements touching the staircase on the periodic table (there are 7 of them), exhibit metallic and nonmetallic properties.

What do elements in the same period on the periodic table have in common?

same energy level/electron shell

What do elements in the same group on the periodic table have in common?

same number of valence electrons