Unit 2 - Atomic Structure

Question 1

Democritus discovered

Studied under Greek Philosopher Leucippus.

Answer 1

matter was composed into tiny particle called “a tomos”

“a tomos:” uncuttable or indivisible

Question 2

JJ Thomson discovered

Answer 2

Estimated mass of rays of cathodes weren’t rays but slightly charged particls or as we call them: electrons

Made the Plum Pudding Method where the pudding is positive and the floating fruit is negative

Question 3

John Dalton discovered

(challenged Aristotle)

Answer 3

Provided first empirial evidence that atoms exist by proposing that compounds consist of different types of atoms in whole # ratios and that chemical reactions involve rearrangements to give new combinations

Billard Ball Model

5 Postulates:
1. All matter is made of atoms
2. All atoms of same element are identical
3. Atoms cannot be created nor destroyed
4. Combine in whole # ratios by mass
5. Atoms can be separated, rearranged, or combined

Question 4

Earnest Rutherford discovered

Answer 4

He experimented with a thin sheet gold foil & screen with zinc sulfide and then bombarded it with particles. Some went through but some deflected meaning that there must be a nucleus with a positive charge.

Most of the atom is empty space.

Question 5

Neils Bohr discovered

Answer 5

electrons in orbits around a central nucleus with each orbit having a specific # of electrons which correlates to energy levels

Planetary Model

Question 6

Quantum Theory

or cloud model or Quantum Mechanical Model

Answer 6

electrons weren’t particles or waves, instead they had properties of both and neither meaning that the arrangement of electrons around a nucleus could only be described in probability.

Question 7

Orbitals

Answer 7

region where an electron is more likely to be found

Question 8

Millikan discovered

Answer 8

charge of electron to be negative

Question 9

Atomic Number (Z)

Answer 9

number of protons, also equals electrons if atom is neutral

Question 10

Mass Number (A)

Answer 10

number of protons & neutrons

Question 11

Neutrons

Answer 11

mass number - atomic number

mass-protons

Question 12

Isotope

Answer 12

atoms with differing numbers of neutrons

Periodic table will show the average atomic mass

i.e.: k-39, k-40, k-41

Question 13

Average Atomic Mass

Answer 13

mass based on the average of all isotopes of an atom

unites are AMU

solve by multipling isotope times abundance, then add each answer to equal average atomic mass

Question 14

Column

up or down

Answer 14

group or family

18 of them

Question 15

Row

side to side

Answer 15

period

7 of them

Question 16

Metals

where are they and what are their properties

Answer 16

left side; heat conductors, malleable, shiny, ductile

Question 17

Non-metals

where are they and what are their properties

Answer 17

right side, opposite metal properties

most are gases

Question 18

Metalloids

Answer 18

found on the stair step line and has properties of both

most common is silicon

Question 19

elements are grouped into ____ based on their ____ properties

Answer 19

families; chemical

Question 20

elements

in the same group

Answer 20

have similar properties, same # of valence electrons, and same oxidation number

-Valence Electrons: electrons that are closer to the nucleus are in filled orbitals and are called core electrons. Valence electrons are the farthest from the positive charge (the protons) and thus tend to be easier to remove than core electrons; this means that it takes them less energy to move far away from the atom.
-Oxidation Number: hypothetical charge of an atom if all of its bonds to other atoms were fully ionic

Question 21

reactivity

for metals and non-metals

Answer 21

metals-reactivity increases as you go down the table
non-metals-reactivity decreases as you go down the table

Question 22

Dmitri Mendeleev

Answer 22

contributed ascending atomic mass

Question 23

Henry Moseley

Answer 23

contributed ascending atomic number