unit 2 list 1 chemistry Flashcards
Atoms
the smallest unit of an element
Molecules
a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
Substances
a particular kind of matter with uniform properties
Homogenous Mixtures
a mixture of two or more substances that are evenly distributed throughou
Heterogenous Mixtures
a mixture in which the composition is not uniform throughout the mixture
Chemical Properties
a property of a substance that is observed when a substance undergoes a chemical change
Physical Properties
a characteristic of a substance that can be observed or measured without changing the identity of the substance
Isotopes
Atoms with the same number of protons but different numbers of neutrons
Elements
a pure substance that cannot be broken down into simpler substances by chemical means, composed of atoms that all have the same number of protons in their nucleus
Compounds
a chemical substance composed of many identical molecules containing atoms from more than one chemical element held together by chemical bonds
Reactants
a substance that takes part in and undergoes change during a reaction
Products
the substances that result from a chemical reaction
Hydrogen Bonds
a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom
Covalent Bonds
a chemical bond that involves the sharing of electrons to form electron pairs between atoms
Ionic Bonds
result from the attraction between oppositely charged ions
Cation
a positively charged ion, i.e. one that would be attracted to the cathode in electrolysis.
Anion
a negatively charged ion, i.e. one that would be attracted to the anode in electrolysis.
Periodic Table-Groups
18 numbered groups on the standard periodic table
Periodic Table Rows
The rows on the periodic table are called periods.
Valence Electrons
the electrons in the outermost shell, or energy level, of an atom
pH scale
measures how acidic or alkaline a substance is
Acids
A chemical that gives off hydrogen ions in water and forms salts by combining with certain metals
Bases
a substance that can accept hydrogen ions (protons) from another substance
