untied 2 List 1 chemistry Flashcards
atoms
An atom is the basic building block of chemistry.
molecules
a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
substance
A substance is simply a pure form of matter. In other words, a substance is matter than contains only one type of atom or molecule.
homogeneous
A homogeneous mixture is one whose composition is uniform throughout the mixture.
Chemical properties
Chemical properties are characteristics that can only be measured or observed as matter transforms into a particular type of matter.
heterogeneous mixtures
A heterogeneous mixture is a mixture in which the composition is not uniform throughout the mixture.
physical properties
A physical property is a characteristic of a substance that can be observed or measured without changing the identity of the substance.
isotopes
Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons.
covalent bond
A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms.
Periodic Table-Groups
Groups are numbered 1–18 from left to right.
Valence Electrons
Valence electrons are the electrons in the outermost shell, or energy level, of an atom.
ph scale
The pH scale measures how acidic or alkaline a substance is.
acids
(A-Sid) A chemical that gives off hydrogen ions in water and forms salts by combining with certain metals.
based
the bottom support of anything; that on which a thing stands or rests
chemical elements
A chemical element is a chemical substance whose atoms all have the same number of protons.
