37 terms

Unit 4 (Periodic Table Trends)

Unit 4 (PT)
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Periodic table
A table in which the chemical elements are arranged in order of increasing atomic #. Elements with similar properties are arranged in the same column (group), and elements with the same number of energy levels arranged in the same row (period).
Group
*A column on the periodic table
Period
*A row on the periodic table
Metals
Large group of elements that tend to be solids at room temp, good conductors of heat and electricity, malleable, ductile, and lustrous
Nonmetals
Group of elements that may be solids, liquids, or gases at room temp and tend to be poor conductors of heat and electricity, and NOT malleable, ductile, or lustrous
Semimetals
Group of elements that have properties of metals or nonmetals, or somewhere inbetween. AKA "metalloids."
Alkali Metals
Highly reactive family of elements that tend to be very soft, shiny metallic solids with low densities and melting points; have 1 valence e-.
Alkaline Earth Metals
Less reactive family of metallic solids with higher densities and melting points than alkali metals; have 2 valence e-.
Halogens
Highly reactive family of nonmetals; all are diatomic; have 7 valence e-
Noble Gases
Completely nonreactive family of nonmetals; have 8 valence e-; all are gases at room temp
Transition Metals
Large block of metals in the center of the periodic table.
Inner Transition Metals
Consists of the lanthanides and actinides; two rows of elements set below the main body of the periodic table
Monoatomic
Exist in nature as single atoms - uncombined with other elements (e.g., Ag, Pt, Au, He, Ne)
Diatomic
Exist in nature in pairs - two of the same atom bonded together (e.g., H2, N2, F2...)
Dmitri Mendeleev
Developed the first widely accepted periodic table in 1869
Periodic law
States that when arranged in order of increasing atomic #, periodic patterns in the properties of the elements emerge
Periodic trend
Describe how properties of the elements change as you move up and down, right and left through the periodic table
Coloumbic Attraction
Refers to the force of attraction between the positively charged nucleus and the negatively charged valence electrons in an atom
Nuclear Charge
The strength of the positive charge in the nucleus of the atom; corresponds to the number of protons the atom has
Atomic Radius
Size of the atom; increases as you move down and to the left in the periodic table
Ionic Radius
Size of the ion; increases as you move down and to the left in the periodic table
1st Ionization Energy
The energy required to remove an atom's most loosely held valence electron; increases as you move up and to the right in the periodic table
Electronegativity
The ability of an atom in a chemical bond to pull shared electrons toward itself; increases as you move up and to the right in the periodic table
Chemical Bond
The force of attraction between atoms that links them together and causes them to behave as a unit
Reactivity
The tendency of elements to react with air, water, acids, bases, etc.
Corrosion
The disintegration of a metal due to its reaction with oxygen, water, or other substances in the environment
Element
*A sample of a single type of atom large enough to weigh on a balance; 118 different ones are currently known
Atom
*The smallest unit of an element that has all the characteristics of that element; consists of a dense, central nucleus containing protons and neutrons that is surrounded by a cloud of electrons
Nucleus
*Small, dense, positively charged center of the atom that contains most of its mass
Atomic Number
*The number of protons in an atom's nucleus; the element's "address" on the periodic table
Average Atomic Mass
*The mass of a single atom; Listed on the periodic table as a decimal # that is the weighted average mass of all known isotopes of an element
Energy levels
*There are up to 7 of these according to the modern model of the atom; Electrons found in the one closest to the nucleus have the lowest energy while those in the outermost one have the highest energy; The row # on the periodic table is the number of these an atom has.
Valence electrons
*Electrons that are in the outermost energy level of an atom; Atoms with the same number of these have similar chemical properties
Electron configuration
*A form of notation which shows how the electrons are distributed among the various atomic orbital and energy levels. The format consists of a series of numbers, letters and superscripts.
Ion
*An atom that has gained or lost electrons to become a charged particle
Anion
*An atom that gained electrons and therefore has a negative charge.
Cation
*An atom that lost electrons and therefore has a positive charge.