Question

observations:

1. the rows (left to right) on the periodic table are called periods. look across the three periods on the partial periodic table above and make note of the similarities and differences you see.

similarities:
differences:

1. the columns (top to bottom) on the periodic table are called groups or families. look down the 7 groups on the partial periodic table above and make note of the similarities and differences you see.

similarities:
differences:

Explanation:

1. Periods:

• Similarities: As you move across a period from left - right, the number of electron shells remains the same. For example, all elements in period 2 have 2 electron shells. Also, the metallic character generally decreases across a period.
• Differences: The atomic number increases by 1 from one element to the next. This leads to an increase in the number of protons, electrons, and a change in chemical properties. For instance, elements on the left are metals, while those on the right are non - metals.

1. Groups:

• Similarities: Elements in the same group have the same number of valence electrons. This gives them similar chemical reactivity. For example, all elements in Group 1 (alkali metals) have 1 valence electron and are highly reactive metals.
• Differences: The atomic size increases as you move down a group. This is because the number of electron shells increases. Also, the ionization energy generally decreases down a group as the outermost electrons are farther from the nucleus and easier to remove.

Answer:

1. Similarities (Periods): Same number of electron shells; Decreasing metallic character.

Differences (Periods): Increasing atomic number; Change in chemical properties from metal to non - metal.

1. Similarities (Groups): Same number of valence electrons; Similar chemical reactivity.

Differences (Groups): Increasing atomic size; Decreasing ionization energy.