chapter 3- atoms

Question 1

big picture of atoms: properties of any substance are related to _________?

Answer 1

its structure

Question 2

______ known elements, ______ are naturally occuring

Answer 2

118, 98

Question 3

Democritus

Answer 3

-400 BCE
-“if we cut something over and over we reach a point to which we can no longer divide it”

Question 4

Antoine Lavoisier

Answer 4

-mid/late 18th century
-Cataloged many chemical reactions
-Law of conservation of mass

Question 5

Law of conservation of mass

Answer 5

In chemical reactions, matter is neither created nor destroyed

Question 6

John Dalton

Answer 6

-mid 18th-mid 19th century

1. elements arr made of tiny, invisible particles called atoms
2. the atoms of each element are unique
3. atoms can join in whole-number ratios to form compounds
4. atoms are unchanged in chemical reactions

Question 7

X-ray crystallography helps scientists:

Answer 7

visualize the arrangement of atoms

Question 8

Dimitri Mendeleev

Answer 8

-late 1860s
-periodic table of elements (60 at the time but predicted more)

Question 9

periods vs groups

Answer 9

horizontal periods, vertical groups

Question 10

Metals

Answer 10

• Lie to the left on the periodic table
  -usually solids at room temp
  -conduct heat and electricity
  -easily molded

Question 11

Nonmetals

Answer 11

• Located on the upper-right on the periodic table
  -range in physical properties
  -primary atomic building blocks for all plant and animal life

Question 12

Metalloids

Answer 12

• Located between metals and non-metals
  -stair step pattern
  -semiconductors heat and electricity
  -essential components of modern electronics

Question 13

Group 1A: Alkali Metals

Answer 13

-soft metals
-react violently with water

Question 14

Group 7A: Halogens

Answer 14

-diatomic molecules in elemental form
-form many different compounds
-bleach, teflon, fire retardants, antisepctics, and table salt include halogens in their compositions

Question 15

Group 8A: Noble Gases

Answer 15

-generally, do not form compounds
-gases at room temprature

Question 16

Electron

Answer 16

tiny, negatively charged particle (1897 JJ Thompson)

Question 17

Plum pudding model

Answer 17

claimed negative electrons spread throughout a positively-charged material

Question 18

Ernest Rutherford

Answer 18

-1909
-the behavior of positively charged alpha particles
-surrounded gold film with a material that glowed when particles struck it. expected the alpha particles to pass through film but some bounced back
-concluded that the atom is mostly empty space with a dense nucleus at the center

Question 19

model of an atom

Answer 19

dense nucleus, in electron cloud, electrons surround outside

Question 20

atomic mass unit (u)

Answer 20

1 u = 1.66 x 10^-27 kg

Question 21

charge affects how particle interacts….

Answer 21

opposite charges attract and like charges repel

Question 22

mass of proton, neutron, electron

Answer 22

1.0073, 1.0087, 0.0005

Question 23

charge of proton, neutron, electron

Answer 23

+1,no charge,-1

Question 24

What holds atoms together

Answer 24

Opposite electrical charges attract eachother

Question 25

Atomic identity

Answer 25

the number of protons determines the identity of the atom

Question 26

Atomic number=

Answer 26

of protons in an atom
and # of electrons in a neutral atom

Question 27

Mass number=

Answer 27

protons + neutrons

Question 28

Isotopes

Answer 28

atoms that have the same atomic number but different mass number

Question 29

Writing atomic symbols

Answer 29

mass number above, atomic number below. symbol to the right

Question 30

Isotopes and atomic weight

Answer 30

Atomic weight = sum of (isotopic abundance)(isotopic mass)