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unit 2
the atom and periodic table
Term | Definition |
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atomic radius | The atomic radius of a chemical element is a measure of the size of its atoms, usually the mean or typical distance from the center of the nucleus to the boundary of the surrounding shells of electrons. |
chemical family | In chemistry, a group is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the f-block columns are not numbered. |
EM spectrum | The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies. |
electronegativity | Electronegativity, symbolized as χ, is the tendency for an atom of a given chemical element to attract shared electrons when forming a chemical bond |
frequency | the number of waves that pass a fixed point in unit time |
ionic radius | Ionic radius, , is the radius of a monatomic ion in an ionic crystal structure. |
ionization energy | ionization energy or ionisation energy is the minimum amount of energy required to remove the most loosely bound electron of an isolated neutral gaseous atom or molecule. |
isotopes | Isotopes are two or more types of atoms that have the same atomic number and position in the periodic table, and that differ in nucleon numbers due to different numbers of neutrons in their nuclei. |
planck's constant | The Planck constant, or Planck's constant, is a fundamental physical constant denoted h, and is of fundamental importance in quantum mechanics. |
valence e | In chemistry and physics, a valence electron is an electron in the outer shell associated with an atom, and that can participate in the formation of a chemical bond if the outer shell is not closed |
wavelength | the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats |
alkali metals | The alkali metals consist of the chemical elements lithium, sodium, potassium, rubidium, caesium, and francium. Together with hydrogen they constitute group 1, which lies in the s-block of the periodic table. |
alkaline earth metals | The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium, magnesium, calcium, strontium, barium, and radium. The elements have very similar properties |
atom | An atom is the smallest unit of ordinary matter that forms a chemical element. |
atomic # | The atomic number or proton number of a chemical element is the number of protons found in the nucleus of every atom of that element. |
avg. 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. |
electrons | The electron is a subatomic particle, whose electric charge is negative one elementary charge. |
electron affinity | The electron affinity of an atom or molecule is defined as the amount of energy released when an electron is attached to a neutral atom or molecule in the gaseous state to form a negative ion. |
halogens | The halogens are a group in the periodic table consisting of five or six chemically related elements: fluorine, chlorine, bromine, iodine (I), and astatine. |
mass # | The mass number, also called atomic mass number or nucleon number, is the total number of protons and neutrons in an atomic nucleus |
neurons | The neutron is a subatomic particle, symbol n or n⁰ , which has a neutral charge, and a mass slightly greater than that of a proton. |
noble gasses | The noble gases make up a class of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. |
nucleus | The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil |
oxidation #s | The oxidation state, sometimes referred to as oxidation number, describes the degree of oxidation of an atom in a chemical compound. |
photon | The photon is a type of elementary particle. It is the quantum of the electromagnetic field including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. |
proton | A proton is a subatomic particle, symbol p or p⁺ , with a positive electric charge of +1e elementary charge and a mass slightly less than that of a neutron. |
speed of light | The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its exact value is defined as 299792458 metres per second. |
transition metals | In chemistry, the term transition metal has three possible definitions: The IUPAC definition defines a transition metal as "an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell |