Chemistry glossary

| Subject classification: this is a chemistry resource.

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## Alpha Particle

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An alpha particle is a helium nuclei, one of the three types of radiation given off by radioactive substances. It has low penetrating power, can be stopped by paper, skin, or clothing, and only travels a few centimeters in air. It has a mass of 4.

## Beta Particle

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A beta particle is an electron, one of the three types of radiation given off by radioactive substances. It has medium penetrating power, can be stopped by 1 mm thick aluminum, and travels a few meters in air. Has a mass of 1/1840.

## Periodic Table

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The Periodic table is a way to show the similarities and differences of the elements. The table is in order of increasing atomic numbers. The table is divided into many groups: the noble gases, halogens, metalloids, nonmetals, metals, alkaline earth metals, inner transition metals, alkali metals, transition metals

## Periods

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A period is a horizontal row on the periodic table. The atomic number increases when moved left to right on each period.

## Periodic Law

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States that there are patterns in chemical and physical properties when the elements are put into order of increasing atomic numbers.

## Gamma Ray

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One of the three types of radiation given off by radioactive substances. It has a high penetrating power, can be stopped 10cm of lead or several meters of concrete, and travels a few kilometers in air.

## Group

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A group is a vertical column on the periodic able. These are also called families. There are 18 groups on the periodic table.

## Representative elements

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All the elements in the groups A. These have all the same amount of valance electrons in their s and p sublevels.

## Metals

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The Metals are one class of elements on the periodic table. Metals are known to usually be lustrous, malleable, ductile, and good conductors of electricity and heat. All metals are solid except for Mercury.

## Alkali Metals

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These elements are located on the left side of the periodic table in the 1A group. These elements are the most reactive out of all the elements on the table. They have 1 valance electron. If these elements are put into water, they produce hydrogen gas.

## Alkaline Earth Metals

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These elements are located in group 2A and are very reactive like the alkali metals, but not as reactive. These elements have 2 valance electrons and when added to water, these elements form a base solution.

## Transition Metals

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These elements are located in group B. These elements look like metals but can act differently than metals sometimes.

## Inner Transition Metals

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These elements are located on the bottom of the periodic table, in the F rows. These elements have large atoms in that they have 6 or 7 energy levels. The top row of the elements are reactive and the bottom row of elements are radioactive.

## Nonmetals

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The nonmetals are located on the right side of the periodic table past the zig-zag line. These elements are the complete opposite of metals, hence their name. These elements are not lustrous, are poor conductors of electricity and heat, and are brittle.

## Halogens

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These elements are located in the group 7A. These elements are nonmetals and are usually used to make salts. They are the most reactive nonmetals and are diatomic elements, which means that they form bonds with themselves.

## Noble Gases

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The Noble Gases are located on the far right column of the periodic table. They are the only completely stable elements that have all of their sublevels filled. These elements are located in group 0 or 8A.

## Metalloids

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These elements have characteristics of both metals and nonmetals.

## Atomic Radius

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The atomic radius is the distance from the nucleus of the atom to the valance electrons on the outside of the atom. The atomic radius of the elements on the periodic table get smaller when moving from left to right, and when moving from the bottom to the top.

## Electronegativity

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Electronegativity is the tendency for an atom to attract electrons to itself when it is chemically combined with another element.

## Ionization Energy

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The ionization energy is the amount of energy required to remove the first electron from an atom.

## Intermolecular Forces

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Intermolecular forces are the attractions between molecules due to their polarities. The physical properties of melting point, boiling point, vapor pressure, evaporation, viscosity, surface tension and solubility are related to the strength of the intermolecular forces between molecules.

Created by Joseph Cox