MCAT Terms Flashcards
Atom
Tiny particles that compose all mass
Nucleas
The center of an atom composed of protons and neutrons surrounded by electrons. Radius 10-4 angstroms.
Angstrom
1 angstrom = 10^-10 meters
Nucleons
Overarching name for protons and neutrons
Atomic Radius
Distance between the nucleus and electrons, approximately 1-3 angstroms
Electron
Negatively charged non-nucleon component of an atom
Electronic Charge
The charge on one electron or one neutron. 1 e is equal to 1.6 x 10^-19
Element
The essential building block of all matter that cannot be broken down into simpler substances by chemical means
Mass Number
The mass of protons and neutrons within an atom. The top number on the left of an elements symbol in the periodic table. Changes with the isotope.
Atomic Number
The weight of only the protons in the nucleus. The bottom number on the elemental symbol in the periodic table. Does not change with the isotope.
Isotopes
Two or more atoms of the same element that contain different numbers of neutrons.
Nuclide
A specific isotope
Atomic Weight
Also known as molar mass, average weight of all the different isotopes of an element. The one it is closest to is the most prevalent.
Mole
A mole of carbon 12 is the number of carbon atoms in twelve grams of carbon. This is given by avogadro’s number.
Avogadro’s Number
6.022 x 10^23
Moles = ?
grams / atomic or molecular weight
The periodic table
A way of organizing elements which lists elements from left to right in order of atomic number. Rows are called periods, columns are called families.
Period (Chemistry)
Rows on the periodic table
Group or Family (Chemistry)
Columns on the periodic table
Metals
Large atoms which tend to lose electrons to form positive ions or positive oxidation states.
Properties of Metals
1) Ductile (Easily Stretched)
2) Malleable (Easily Flattened)
3) Thermal and Electrical Conductivity
4) Lustrous
Non-Metals
Have diverse appearances and chemical behaviors. Tend to form negative ions. Typically have lower melting points than metals.
Alkali Metals
The first group (1A) of the periodic table. Easily form 1+ cations. Low melting point and low density metals. React with hydrogens to form hydrides. React exothermically with water.
Alkaline Earth Metals
The second group (2A) of the periodic table. Easily form 2+ cations. Less reactive, more dense, higher melting point, and harder than alkali metals. Heavier ones are more dense than lighter ones.
Group 4A Elements
The fourth A group on the periodic table. Can easily form four covalent bonds. Can form two pi bonds to form double or triple bonds. Can form two additional bonds with lewis bases.
Halogens
Radioactively stable group 7A elements. Flourine, chlorine, bromine, and iodine. All are diatomic gases at room temperature except bromine.
Noble Gases
Also known as inert gases. The group 8A elements. Non reactive. Found in nature as isolated atoms.
Effective Nuclear Charge
The amount of nuclear charge experience by the second electron present in an atom. Zeff is the result of electron shielding.
Periodic Trends
Totalities of predictions made by coulombs law as a result of Zeff and atomic radius.
Ionization Energy
The energy needed to detach an electron from the nucleus. Increases from left to right and from bottom to top.
Second Ionization Energy
The energy required for the removal of the second electron from the same atom.
Electronegativity
The tendency of an atom to attract an electron in a bond it shares with another atom. Increases from left to right and from bottom to top.
Electron Affinity
The willingness of an atom to accept an additional electron. Increases from left to right and from bottom to top.
Metallic Character
Increases from right to left and from bottom to top.
Trends increasing from left to right and from bottom to top.
Energy of Ionization, Electron Affinity, and Electronegativity
Trends increasing from right to left and from top to bottom
Atomic radius and metallic character
