unit 2 chem vocab

Electron Configuration

Arrangement of electrons in an atom

Ground State

When an electron is at the lowest available energy level

Excited State

When an electron is in a higher energy level than normal

Orbital

An area of space in an atom that can hold a mass of 2 electrons

Ion

An atom/molecule with a charge

Wavelength

Distance between 2 adjacent crests or troughs (represented by lambda)

Frequency

Number of peaks that pass a point per second (represented by nu)

Paired Electrons

2 electrons that occupy the same orbital and have opposite/parallel spins

Quantum Model

More modern model of an atom the shows the possible positions of an electron in an electron cloud, where electrons move in waves

Pauli Exclusion Principle

No 2 electrons in an atom can have the same 4 quantum numbers

Hund’s Rule

When electrons have a choice of entering two equal orbitals they enter the orbitals so that a maximum number of unpaired electrons result, and the electrons have parallel spins

Aufbau Principle

Electrons must be placed in order of energy

Unpaired Electrons

Electrons that are by themselves on an orbital

Valence Electrons

An electron on the outermost energy level of an atom and takes part in chemical reactions

Core Electrons

Electrons that occupy the lower energy levels and do not take part in chemical reactions

Proton

• Positively charged subatomic particle with a mass of 1 AMU

• Located in the nucleus

• The number of protons in an atom is the same value as its atomic number

  • The proton count dictates the element’s identity

  • The proton count is part of the atom’s mass number

Neutron

• Neutrally-charged subatomic particle with a mass of 1 AMU

• Located in the nucleus

• The number of neutrons in a nucleus can affect the stability of an atom

  • The neutron count is part of the atom’s mass number

  • Each elemental atom has a different acceptable numbers of neutrons allowed

Each acceptable proton:neutron ratio for the same element is called an isotope of the element

Electron

• Negatively-charged subatomic particle with a negligible mass

• Located in orbitals surrounding the nucleus (collectively called the electron cloud)

The number of valence electrons in an atom dictates how it will react chemically with other atoms

Isotope

One of multiple stable atoms of the same element, with a different mass number

Each acceptable proton:neutron ratio for the same element is called an isotope of the element

All isotopes of an element take part in calculating the element’s average atomic mass

This is why the
mass values on
the periodic table
have decimal

Atomic number

the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table

Average atomic mass

The average atomic mass (sometimes called atomic weight) of an element is the weighted average mass of the atoms in a naturally occurring sample of the element

Mass number

the total number of protons and neutrons in a nucleus

AZX notation

used to state the chemical representation of an element

X is the atomic symbol of the element, A is the mass number and Z is the atomic number

Atom

the basic unit of a chemical element

Electromagnetic radiation

a kind of radiation including visible light, radio waves, gamma rays, and X-rays, in which electric and magnetic fields vary simultaneously

radio waves, microwaves, infrared light, visible light, uv rays, x rays, gamma rays

Photon

a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass

Discrete energy levels

electrons can only be exists on as fixed energy level and not in-between

Quantized

elections can only be allowed in certain locations, has discrete energy levels

Orbital diagram

diagrams used to show the energy of electrons within the sublevels of an atom or atoms when used in bonding

Orbitals

an area of space in an atom that can hold 2 elections