Unit A: Chemical Change Flashcards
Element
Is a pure substance that cannot be broken down into simpler substances by chemical means.
Atom
It is the smallest part of an element that has all the properties of that element.
Atomic Number
Is the number of protons in the nucleus of an atom. (The number on the top left hand corner)
Atomic Mass
The average mass of the atoms of an element including all isotopes. (The number under the name of an element)
Energy Level
A specific region surrounding the nucleus that is available for electrons.
Valence Electron
An electron that occupies the outermost energy level in an atom.
Lewis Dot Diagram
A representation of an atom that shows only valence electrons.
Anion
A negatively charged ion.
Cation
A positively charged ion.
Metal
A malleable and ductile element that has luster, has good heat and electrical conductivity and tends to form positive ions.
Non-Metal
An element that is not flexible, does not conduct electricity and tends to form negative ions.
Compound
A pure substance formed from atoms of two or more elements with the different atoms joined in fixed ratios
Ionic Compound
A pure substance formed from a metal and nonmetal
Ionic Bond
A bond formed by the simultaneous attraction between positive and negative ions.
Molecular Compound
A pure substance formed from non-metals. (Right side of the stair case)
Covalent Bond
A bond formed by the simultaneous attraction of two nuclei for a shared pair of electrons.
Molecule
A particle containing a fixed number of covalently bonded, non-metal atoms.
Chemical Change
A change in which one or more new substances with different properties is formed
Mass Number
The total number of protons and neutrons in an atom.
Ion
An electrically charged atom or group of atoms.
Exothermic Change
A chemical change in which energy, usually in the form of heat is released into the surrounding
Endothermic Change
A chemical change in which energy is absorbed from the surrounding - making cold.
Solution
A homogeneous mixture of dissolved substances that contains a solute and a solvent
Aqueous Solution
A solution in which water is the solvent.