CHAPTER 7 - Periodic Properties of Elements

VALENCE ORBITALS

Orbitals that contain the outer-shell electrons of an atom.

EFFECTIVE NUCLEAR CHARGE

The net positive charge experienced by an electron in a many-electron atom; this charge is not the full nuclear charge because there is some shielding of the nucleus by the other electrons in the atom.

BONDING ATOMIC RADIUS

The radius of an atom as defined by the distances separating it from other atoms to which it is chemically bonded.

ISOELECTRONIC SERIES

A series of atoms, ions, or molecules having the same number of electrons.

IONIZATION ENERGY

The energy required to remove an electron from a gaseous atom when the atom is in its ground state.

ELECTRON AFFINITY

The energy change that occurs when an electron is added to a gaseous atom or ion.

METALLIC CHARACTER

The extent to which an element exhibits the physical and chemical properties characteristic of metals.

ALIKALI METALS

Members of Group 1A in the periodic table.

ALKALINE EARTH METALS

Members of Group 2A in the periodic table.

OZONE

The name given to O3, an allotrope of oxygen.

HALOGENS

Members of group 7A in the periodic table.

NOBLE GASES

Members of group 8A in the periodic table.

MENDELEEV

Created the first periodic table. Arranged elements by increasing atomic mass.

MOSELEY

Arranged the periodic table according to atomic number instead of mass.

IONIC RADII

Radius of an ion.

ELECTRONEGATIVITY

A measure of the ability of an atom in a chemical compound to attract electrons.

NONMETALLIC CHARACTER

Ability to gain electrons resulting in the following properties: brittle, dull, electrical and thermal insulators, most oxides are acidic and molecular, form anions and polyatomic ions.

METALLOIDS

Elements that have properties of both metals and nonmetals.

HYDRIDE ION

An ion formed by the addition of an electron to a hydrogen atom: H- .

Across a Period, Atomic Radius ?

Decreases. Why? Greater Positive Nuclear Charge

Down a Group, Atomic Radius ?

Increases. Why? 1) Increased number of energy levels 2) Increased electron repulsion 3) Shielding Effect

Across a Period, Ionization Energy ?

Increases. Why? Greater Positive Nuclear Charge

Down a Group, Ionization Energy ?

Decreases. Why? 1) Increased number of energy levels 2) Increased electron repulsion 3) Shielding Effect

Ionic Radius of Metals are ?

Smaller Why? Same # Protons Hold on to Fewer Electrons More Effectively.

Ionic Radius of Nonmetals are ?

Large Why? Same # Protons Hold on to More Electrons Less Effectively.

Metals gain or lose electrons?

Lose electrons to become a cation.

Nonmetals gain or lose electrons?

Gain electrons to become an anion.

Across a Period, Electronegativity ?

Increases. Why? Greater Positive Nuclear Charge

Down a Group, Electonegativity ?

Decreases. Why? 1) Increased number of energy levels 2) Increased electron repulsion 3) Shielding Effect

Across a Period, Electron Affinity ?

Generally Increases (More Negative Value) . Why? Greater Positive Nuclear Charge