Gre Chemistry Flashcards
Mass number
Total number if protons and neutrons in the nucleus represented by letter A
Atomic number
Total number if protons in the nucleus represented by letter Z
Isotope
Two or more nuclei of the same element that have different mass numbers
Binding energy
Energy required to overcome proton proton repulsion and hold the nucleus together
Parent nucleus
Nucleus prior to nuclear decay
Daughter nucleus
Nucleus formed as a result of nuclear decay
Alpha decay
Helium nuclei 2 protons 2 neutrons
Beta decay
Releases electron daughter will always be different element but will have the same mass
Gamma decay
Daughter is identical to parent except it has less energy
First order decay
Probability that a nucleus will decay in a given time is constant and independent of surroundings.
the rate of loss of mass at any given time is directly proportional to the mass present at that time.
Nuclear fission
When an accelerated particle such as a neutron striking a nuclei the nucleus can split into two or more fragments
Nuclear fusion
Accelerated particle captured by nucleus to create larger nucleus
Bohr atom
Atom with only one electron
Energy shells
Certain distances away from the nucleus
Ground state
Configuration where electrons are in lowest energy levels
Excited state
Configuration where electrons are not in lowest energy levels
Valences electrons
Electrons with the largest value of n
Principle quantum number
n, energy level > or equal to n
Secondary quantum number
I, angular momentum, 0-n
Degenerate
Quantum states or configurations that have identical energies
Magnetic quantum number
quantum number that identifies different orbitals within a subshell. ml can take on values from -l to +l. The number of orbitals within a subshell is the number of possible magnetic quantum number values.
S
1 orbital
P
3 orbitals
D
5 orbitals
F
7 orbitals
Spin quantum number
The fourth quantum number denoted by ms. The spin quantum number indicates the orientation of the intrinsic angular momentum of an electron in an atom. The only possible values of a spin quantum number are +½ or -½ (sometimes referred to as ‘spin up’ and ‘spin down’).
Pauli exclusion principle
The Pauli exclusion principle states no two electrons can have the identical quantum mechanical state in the same atom.
No pair of electrons in an atom can have the same quantum numbers n, l, ml and ms.
Aufbau principle
no two electrons in the atom will share the same four quantum numbers n, l, m, and s.
electrons will first occupy orbitals of the lowest energy level.
electrons will fill an orbital with the same spin number until the orbital is filled before it will begin to fill of the opposite spin number.
electrons will fill orbitals by the sum of the quantum numbers n and l. Orbitals with equal values of (n+l) will fill with the lower n values first.
Hunds rule
When partially filling degenerate orbitals of p and d and f always put one electron in each orbital before pairing them up. Orient them so their magnetic spins are all the same
Atomic size trend
Increases as one moves down or to the left in the periodic table
Atomic and ionic radii
Cation < neutral < anion
Isoelectronic species
Two atoms or ions that have the same number of electrons
Ionization
Removal of an electron from a neutral atom
Endergonic process
Requires input of energy
Ionization energies
The first ionization energy is the energy required to remove one electron from the parent atom. The second ionization energy is the energy required to remove a second valence electron from the univalent ion to form the divalent ion, and so on. Successive ionization energies increase. The second ionization energy is always greater than the first ionization energy.
Electron affinity
Electron affinity reflects the ability of an atom to accept an electron. It is the energy change that occurs when an electron is added to a gaseous atom. Atoms with stronger effective nuclear charge have greater electron affinity.
Exergonic
Exergonic refers to a chemical reaction where the free energy of the system decreases.
Electro negativity
Electronegativity is related to ionization energy. Electrons with low ionization energies have low electronegativities because their nuclei do not exert a strong attractive force on electrons. Elements with high ionization energies have high electronegativities due to the strong pull exerted on electrons by the nucleus.
Increases as you move up and to the right
Acidity
Increases as one moves down and to the right
Basicity
Increases as one moves up and to the left
Octet
An eight electron arrangement in the outer electron shell of the noble gases
Cation
Positively charged ion
Anion
Negatively charged ion
Metalloids
Metalloids are located along the line between the metals and nonmetals in the periodic table. The metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Polonium
Properties of metalloids
The reactivity of the metalloids depends on the element with which they are reacting. For example, boron acts as a nonmetal when reacting with sodium yet as a metal when reacting with fluorine. The boiling points, melting points, and densities of the metalloids vary widely. The intermediate conductivity of metalloids means they tend to make good semiconductors.