Chapter 4 : Models of the Atom

Question 1

when was the concept of the atom “born”

Answer 1

450 B.C.

Question 2

what Greek philosopher argued matter is discontinuous and could not be infinitely divided?

Answer 2

Democritus

Question 3

in 350 B.C. who argued matter and motion are continuous

Answer 3

Aristotle

Question 4

In 1803 who argued Aristotle’s proposal and claimed matter as discontinuous and offered experimental evidence to his claim (which Aristotle did not)

Answer 4

John Dalton

Question 5

what are the five parts to the atomic theory

Answer 5

1. an element is compose of tiny, indivisible, indestructible particles called atoms
2. all atoms of an element are identical and have the same properties
3. atoms of different elements combine to form compounds
4. compounds contain atoms in small whole number ratios
5. atoms can combine in more than one ratio to form different compounds

Question 6

Define: electron

Answer 6

a negatively charged subatomic particle having a tiny mass

Question 7

Define: proton

Answer 7

a positively charged subatomic particle with a mass of 1 amu

Question 8

in 1903 who proposed a subatomic model of the atom which pictured a positively charged atom containing negatively charged electrons?

Answer 8

JJ Thomson

Question 9

who coined the terms alpha ray, beta ray, and gamma ray. and found that alpha rays contained particles identical to those of helium atoms stripped of electrons

Answer 9

Rutherford

Question 10

Define: atomic nucleus

Answer 10

a region of very high density in the center of the atom that contains protons and neutrons

Question 11

What is: powerful alpha particles should pass through a homogeneous plum pudding gold atom. Because positively charged alpha particles are deflected, Rutherford reasoned correctly that a gold atom has a dense, positively charged nucleus

Answer 11

Alpha-Scattering

Question 12

where is most of the mass of an atom found

Answer 12

the nucleus

Question 13

Define: neutron

Answer 13

a neutral subatomic particle with a mass of 1 amu which is approximately equal to the mass of a proton

Question 14

what is the location, relative charge, and relative mass of an electron

Answer 14

Location: outside the nucleus
Relative charge: -1
Relative mass: 1/1836

Question 15

what is the location, relative charge, and relative mass of a proton

Answer 15

Location: inside nucleus
Relative charge: +1
Relative mass: 1

Question 16

what is the location, relative charge, and relative mas of a neutron

Answer 16

Location: inside nucleus
Relative charge: 0
Relative mass: 1

Question 17

Define: atomic number

Answer 17

a number that identifies a specific element . a value that indicates the number of protons in the nucleus of an atom

Question 18

Define: atomic notation

Answer 18

a symbolic method for expressing the composition of an atomic nucleus; the mass number and atomic number are indicated to the left of the chemical symbol for the element

Question 19

Define: mass number

Answer 19

A value that indicates the number of protons and neutrons in the nucleus of a given atom

Question 20

Define: isotopes

Answer 20

atoms of the same element that have a different number of neutrons in the nucleus
as the number of neutrons vary, so does the mass

Question 21

how do you refer to an isotope

Answer 21

state the name of the element followed by its mass number