Chemistry: The Periodic Table Quiz

Periodic Table of Elements

• A chemical element is a pure substance that is composed of only one type of atom.
• Atomic number represents the number of protons in the nucleus of an atom.
• Elements are arranged in the periodic table according to ascending atomic number.
• Elements are grouped into metals, metalloids, and nonmetals.
• Metals are typically found on the left side of the periodic table and are often conductive to electricity, malleable, shiny, and sometimes magnetic.
• Nonmetals are typically found on the right side of the periodic table and are often poor conductors of electricity, not malleable, non-shiny, and not magnetic.
• Metalloids have properties that fall between metals and nonmetals; they are typically semiconductors.

History of the Periodic Table

• Antoine Lavoisier (1743-1794) published a list of elements in 1789, which formed the basis for the modern list of elements and classified them into metals and non-metals.
• Johann Döbereiner (1780-1849) classified elements into triads (groups of three elements with related properties and weights).
• John Newlands (1837-1898) proposed the Law of Octaves, noting that elements repeated their chemical properties every eighth element, similar to octaves in music.
• Dmitri Mendeleev (1834-1907) arranged elements based on their atomic mass and observed properties, and listed similar elements in the same family/group. His table also had gaps for undiscovered elements, which turned out to be correct.
• Henry Moseley (1887-1915) arranged elements based on increasing atomic number, which was more fundamental than atomic mass.

Horizontal Rows and Vertical Columns

• The horizontal rows on the periodic table are called periods.

• Elements in the same period have the same number of electron orbitals.

• There are seven periods on the table.

• The vertical columns on the periodic table are called groups or families.

• Elements in the same group have very similar properties and the same number of valence electrons.

• There are 18 groups on the table.

Major Classes of Elements

• Metals, metalloids, and nonmetals are the major classes on the periodic table.

Metals

• Metals are characterized by high electrical conductivity, luster (shine), and malleability (ability to be shaped). They readily lose electrons to form positive ions (cations).
• Most of the elements on the periodic table are metals at room temperature.

Nonmetals

• Nonmetals lack metallic attributes and are good insulators of heat and electricity.
• They are typically found on the right side of the table, except for hydrogen.

Metalloids

• Metalloids have properties that fall between metals and nonmetals.
• They are often semiconductors (conduct electricity under specific conditions).

Alkali Metals

• Alkali metals are highly reactive elements found in Group 1.
• They readily lose one electron to form positive ions (cations).
• They react violently with water to form hydroxides.

Alkaline Earth Metals

• Alkaline earth metals are reactive metals in Group 2.
• They readily lose two electrons to form positive ions (cations).
• They react with water, but are less reactive than alkali metals.

Transition Metals

• Transition metals are versatile elements in Groups 3-12.
• They have valence electrons in multiple shells.
• They are used in manufacturing, construction, and the medical field.

Halogens

• Halogens are nonmetals in Group 17.
• Their reactivity decreases down the group.
• They are highly reactive and exist as diatomic molecules (two atoms per molecule) in nature.

Noble Gases

• Noble gases are chemically inert elements in Group 18.
• They have a full outermost electron shell, making them stable and largely unreactive.
• They are commonly found as monatomic (single-atom) gases.

Lanthanides

• The lanthanides are a series of metallic elements in the periodic table.
• They are also called the rare earth elements.

Actinides

• The actinides are a series of radioactive metallic elements in the periodic table (atomic numbers 89-103).
• They are also radioactive.
• They are often found in nature as radioactive elements.

Periodic Trends

• Atomic Radius: Increases down a group and to the left of the periodic table.
• Ionization Energy: Increases up a group and to the right of the periodic table.
• Electronegativity: Increases up a group and to the right of the periodic table.
• Metallic Character: Increases down a group and to the left of the periodic table.
• Ionic Radius: Cations have smaller ionic radii than their parent atoms because electrons are removed; anions have larger ionic radii than their parent atoms because electrons are added.