Chapter 3: Atoms: The essential building blocks

Question 1

Atomic theory

Answer 1

1) elements are made of tiny particles (atoms)

2) each atom in an element is unique

3) atoms are not changed but combine into a whole number ratios

4) atoms are unchanged in chemical reactions

Question 2

alpha particles

Answer 2

composite particles consisting of two protons and two neutrons tightly bound together

Question 3

Law of conservation of mass

Answer 3

matter is neither created nor destroyed in chemical reactions
-atoms are rearranged in chemical reactions

Question 4

Isotopes:

Answer 4

atoms that have the same atomic number but a different mass number
-can also have the same amount of protons but different number of nuetrons

Question 5

Atomic number

Answer 5

the number of protons in an atom

Question 6

Mass number

Answer 6

the number of protons + the number of nuetrons

Question 7

Atomic Mass

Answer 7

The atomic mass of an element is the weighted average of the atomic masses of the naturally occurring isotopes of that element.

Question 8

Weighted Average

Answer 8

determined by multiplying the percent of natural abundance by the actual mass of the isotope then adding all the products together

Question 9

Ions

Answer 9

atoms or groups of atoms that contain an overall charge

Question 10

Cations

Answer 10

positively-charged ions

Question 11

Anions

Answer 11

negatively-charged ions

Question 12

plum pudding model

Answer 12

atoms are solid and the electrons are spread through a positive layout

Question 13

Bohr Model

Answer 13

electrons orbit the nucleus

Question 14

Scanning Tunneling Microscopy

Answer 14

visualize atoms on a metal surface, to manipulate atoms

Question 15

Ernest Rutherford

Answer 15

surrounded the gold film with a material that glowed when particles struck it.
* expected the alpha particles to pass through the film and hit behind it but some small number of the particles deflected off the film, and back toward the alpha particle source!
-Conclusion: The atom is mostly empty space, with a dense nucleus at the center.