Chapter 4

Question 1

Democritus

Answer 1

Greek philosopher

believed atoms were indivisible/indestructable

Question 2

John Dalton

Answer 2

used experimental methods to transform Democritus’s ideas on atoms into a scientific theory

Question 3

Dalton’s Atomic Theory

Answer 3

1. All elements are composed of tiny indivisible particles called atoms.
2. Atoms of the same element are identical. The atoms of one element are different from the atoms of another element.
3. Atoms of different elements can physically mix together or can chemically combine in simple whole-number ratios to form compounds.
4. Chemical reactions occur when atoms are separated, joined, or rearranged.

Question 4

Flaws in Dalton’s Atomic Theory

Answer 4

1. FALSE- bc atoms are divisible (subatomic particles)
2. FALSE- bc atoms of same element aren’t necessarily identical (isotopes)
3. atoms can’t “physically mix”

Question 5

The Atom

Answer 5

smallest particle of an element that retains its identity during a chemical reaction
2 parts: nucleus, electron cloud

Question 6

Protons

Answer 6

(+) charge
in nucleus
Mass: 1.67 x 10^-24 grams

Question 7

Electrons

Answer 7

(-) charge
outside nucleus (electron cloud)
Mass: much smaller than protons and neutrons; negligible so 0 amu

Question 8

Neutrons

Answer 8

no charge
in nucleus
Mass: 1.67 x 10^-24 grams

Question 9

atomic number

Answer 9

above symbol of element

= number of protons and electrons

Question 10

atomic mass

Answer 10

weighted average of the mass numbers of all isotopes of that elementp

Question 11

mass numbers

Answer 11

sum of protons and neutrons in an atoms

Question 12

ions

Answer 12

atoms that have gained or lost electrons

Question 13

isotopes

Answer 13

atoms of the same element with a different number of neutrons (and mass numbers)