1. give examples of properties of elements that appear in a pattern on the periodic table.

Brief Explanations:

The periodic table arranges elements by atomic number. Properties like atomic radius (decreases across a period and increases down a group), ionization energy (increases across a period and decreases down a group), and electronegativity (increases across a period and decreases down a group) show patterns.

Answer:

Atomic radius, ionization energy, electronegativity