click below
click below
Normal Size Small Size show me how
Vocab B-2
Mrs. Weaver's Science class vocab B-2
Term | Definition |
---|---|
Atomic Mass | The average mass of the atoms of an element. |
Atoms | The basic structural unit of matter; the smallest particle of an element that can enter a reaction. |
Chemical Formula | A shorthand notation to describe elements and compounds and their reactions. Reactions are represented as equations with an arrow indicating direction of change instead of an equals sign. |
Chemical Reactivity | The likelihood that an element or chemical will react with another element or chemical. |
Compound | A homogeneous, pure substance composed of two or more essentially different elements that are chemically combined and that are thus present in definite proportions. |
Gas | A state of matter where the atoms or molecules are farther apart than in a liquid and moving faster than a liquid. |
Electron | An electrically charged negative particle found outside the center of an atom. It is exactly opposite in electrical charge to a proton, but is almost 2,000 times smaller in mass. It is much smaller than an atom and is called a sub-atomic particle. |
Electron Cloud | Area surrounding the nucleus of an atom where the electrons orbit at very high speeds. |
Element | A collection of atoms of one type that cannot be decomposed into any simpler units, except by spontaneously changing into other units by radioactive processes. |
Family (of Elements) | A grouping of elements based on similar chemical properties. Families are generally arranged in columns in the periodic table. |
Liquid | A state of matter where the atoms or molecules are packed less closely than a solid but more closely than a gas and moving more than a solid. |
Metal | Category of elements that usually have a shiny surface, are generally good conductors of heat and electricity, and can be melted or fused, hammered into thin sheet, or drawn into wires. |
Molecule | The smallest particle of an element or compound that displays properties the substance in quantity. |
Neutron | A particle having the same mass as a proton but no electric charge. It is contained in the center (nucleus) of an atom. |
Particle | Atoms or molecules of a substance. All matter is made of particles that are in constant motion. Atoms are the building blocks of matter. Two or more similar or dissimilar atoms can combine to form a molecule. |
Periodic Table of Elements | An arrangement of the elements according to their atomic numbers so that elements with similar properties are in the same column. In 1869, Dmitri I. Mendeleev designed the first periodic table to show the similarities and differences of the elements. |
Proton | The positively charged particle(s) contained in the center of an atom. The number of protons an individual atom has determines what element it is. |
Solid | A state of matter where the atoms or molecules are packed closely together and do not move freely. |
State of Matter | One of the distinct forms that matter takes on. |