Small, dense center of an atom composed of protons and neutrons
Nucleus
Positively charged subatomic particle located in the nucleus of atoms
Proton
A subatomic particle located in the nucleus of atoms that has no charge
Neutron
A negatively charged subatomic particle located in energy levels around the nucleus of atoms
Electron
The electrons in the outermost energy level of an atom
Valence electron
The basic building blocks of matter and are composed of just one type of atom
Element
The number of protons in the nucleus of an atom which identifies the element
Atomic Number
The mass of an atom which is the total number of protons and neutrons in the nucleus of an atom
Mass number
The average mass of all the isotopes of an element
Atomic Mass
Each verticle column of elements on the periodic table
Family/group
Each horizontal row of elements on the periodic table
Period
A property of matter that describes a substance based on its ability to change into a new substance with different properties
Chemical property
A property of matter that can be observed or measured without changing the identiy of the matter
Physical property
A change that occurs when one or more substances are changed into entirely new substances with differenct properites.
Chemical change
A change that affects the siz, shape, phase or color of a substance but does not affect is composition. The same substance or substances remain. No new ones are formed
Physical change
Elements that are shiny, ductile, and malleable and are good conductors or thermal energy and electrical current
Metals
Elements that are not shiny and are poor conductors of thermal energy and electric current
Non-metals
Elements that have properties of both metals and nonmetals; sometimes referred to as semiconductors.
Metalloids
Materials that reduce or inhibit the transfer of thermal energy and electric current
Insulators
Materials that conduct thermal energy and electric current very well
Conductors
The process by which one or more substances change to produce one or more different substances
Chemical reaction
A chemical reaction which absorbs heat energy
Endothermic chemical reaction
A chemical reaction in which heat energy is released.
Exothermic chemical reaction
A shorthand or abbreviated way to write the name of a chemical element
Chemical symbol
A shorthand description that uses chemical formulas to describe a chemical reaction.
Chemical equation
The starting substance or substances in a chemical reaction
Reactants
The substance or substances that are formed in a chemical reaction
Products
A charged particle that forms during chemical changes when one or more valence electrons transfer from one atom to another
Ch.18 LTI-MA 509
