chapter 3 (compounds, physical and chemical changes) Flashcards
chemical bonds
links between two or more atoms that hold atoms together
covalent compound
non-metal atoms combine by sharing electrons to form molecules. ex; carbon dioxide & water
molecule
a group of atoms in which the atoms are bound together by sharing one or more pairs of electrons
ionic compound
atoms gain or lose electrons to form ions. oppositely charged ions come together because of mutual attraction. ex; table salt is made from sodium & chlorine
ionic lattice
a repeating pattern of positive and negative ions forming an ionic compound
polyatomic ion
a molecular ion composed of more than one type of atom joined by covalent bonds. (poly = many)
physical change
a change in the state of matter, the appearance of a subject changes, but no new substances are produced. ex; the melting of a chocolate bar.
chemical change
a change which produces a new substance with new properties. ex; rust forming on a nail
reactants
substances that react in a chemical reaction
products
new substances formed in a chemical reaction
exothermic
a chemical change that releases energy, heat, light, and sound
endothermic
a chemical change that absorbs energy
