chapter 3 (compounds, physical and chemical changes)

Question 1

chemical bonds

Answer 1

links between two or more atoms that hold atoms together

Question 2

covalent compound

Answer 2

non-metal atoms combine by sharing electrons to form molecules. ex; carbon dioxide & water

Question 3

molecule

Answer 3

a group of atoms in which the atoms are bound together by sharing one or more pairs of electrons

Question 4

ionic compound

Answer 4

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

Question 5

ionic lattice

Answer 5

a repeating pattern of positive and negative ions forming an ionic compound

Question 6

polyatomic ion

Answer 6

a molecular ion composed of more than one type of atom joined by covalent bonds. (poly = many)

Question 7

physical change

Answer 7

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.

Question 8

chemical change

Answer 8

a change which produces a new substance with new properties. ex; rust forming on a nail

Question 9

reactants

Answer 9

substances that react in a chemical reaction

Question 10

products

Answer 10

new substances formed in a chemical reaction

Question 11

exothermic

Answer 11

a chemical change that releases energy, heat, light, and sound

Question 12

endothermic

Answer 12

a chemical change that absorbs energy