Term | Definition |
Periodic Table | the chart scientists use to organize and classify all the known elements |
Element | a pure substance that cannot be broken down into simpler substances by chemical reactions |
Element Symbol | a code for a chemical element. It is usually derived from the modern name of the element but for some elements it is derived from the name in Latin. |
Atomic Number | the number of protons in the nucleus of an atom; atomic number determines the chemical properties of the atom |
Atomic Mass | The combined mass of all of the protons and neutrons of an atom. Since each proton and neutron has a mass of approximately one unit (called an atomic mass unit) the atomic mass is approximately equal to the number of protons and neutrons. |
Period | a length of time |
Group | (also known as a family) is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table, but the f-block columns (between groups 2 and 3) are not numbered. |
Family | a group cause they are the same |
Chemical formula | is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, |
Metals | a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity |
Nonmetals | an element or substance that is not a metal. |
Metalloids | an element whose properties are intermediate between those of metals and solid nonmetals. They are electrical semiconductors. |
Noble Gases | any of the gaseous elements helium, neon, argon, krypton, xenon, and radon, occupying Group 0 (18) of the periodic table. They were long believed to be totally unreactive but compounds of xenon, krypton, and radon are now known. |
Reactivity | the state or power of being reactive or the degree to which a thing is reactive. |
Dmitri Mendeleev | Dmitri Ivanovich Mendeleev was a Russian chemist and inventor. He formulated the Periodic Law, created a farsighted version of the periodic table of elements, |
Trend | As you move down a group, atomic radius increases. As you move across a period, atomic radius decreases. |
Energy Level | the fixed amount of energy that a system described by quantum mechanics, such as a molecule, atom, electron, or nucleus, can have. |
Valence Electrons | is an electron that is associated with an atom, and that can participate in the formation of a chemical bond; in a single covalent bond, both atoms in the bond contribute one valence electron in order to form a shared pair. |
Chemical Property | a property or characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed |
Physical Property | a characteristic that can be observed, such as texture, color, odor, melting point, boiling point, density, or measured such as mass, length, volume, that is used to describe matter and can be observed or measured without changing its composition |