Chapter 5: The Periodic Table and Periodic Law

1. Periodic Law
Definition: States that when the elements are arranged by increasing atomic number, there is a periodic repetition of their properties.

2. Groups
Definition: A vertical column of elements in the periodic table arranged in order of increasing atomic number; also called a family.

3. Periods
Definition: A horizontal row of elements in the modern periodic table.

4. Representative Elements
Definition: Elements from groups 1, 2, and 13-18 in the modern periodic table, possessing a wide range of chemical and physical properties.

5. Transition Elements
Definition: Elements in groups 3-12 of the modern periodic table and are further divided into transition metals and inner transition metals.

6. Metals
Definition: An element that is solid at room temperature, a good conductor of heat and electricity, and generally is shiny; most metals are ductile and malleable.

7. Alkali Metals
Definition: Group 1 elements, except for hydrogen, they are reactive and usually exist as compounds with other elements.

8. Alkaline-Earth Metals
Definition: Group 2 elements in the modern periodic table and are highly reactive.

9. Lanthanide Series
Definition: In the periodic table, the f-block elements from period 6 that follow the element lanthanum.

10. Actinide Series
Definition: In the periodic table, the f-block elements from period 7.

11. Nonmetals
Definition: Elements that are generally gases or dull, brittle solids that are poor conductors of heat and electricity.

12. Halogens
Definition: Highly reactive group 17 elements.

13. Noble Gases
Definition: Extremely unreactive group 18 elements.

14. Metalloids
Definition: An element that has physical and chemical properties of both metals and nonmetals.

15. Atomic Radius
Definition: The measure of the size of an atom, typically defined as half the distance between the nuclei of two identical atoms that are bonded together.

16. Ion
Definition: An atom or bonded group of atoms with a positive or negative charge.

17. Ionization Energy
Definition: The energy required to remove an electron from a gaseous atom; generally increases in moving from left-to-right across a period and decreases in moving down a group.

18. Octet Rule
Definition: States that atoms lose, gain, or share electrons in order to acquire the stable electron configuration of a noble gas.

19. Electronegativity
Definition: Indicates the relative ability of an element’s atoms to attract electrons in a chemical bond.