chem chapter 2

Question 1

What did JJ Thomas discover?

Answer 1

Electrons

Question 2

How did JJ Thomas discover electrons?

Answer 2

Beam from the cathode ray tube is deflected toward a positively charged plate.

Question 3

plum pudding model

Answer 3

electrons are distributed throughout positively charged sphere

Question 4

What did Robert Mullikan discover?

Answer 4

The mass and charge of an electron

Question 5

How did Robert Mullikan discover the mass of electrons?

Answer 5

His oil drop experiment measured the electric charge of a single electron

Question 6

What did Henri Becquerel discover?

Answer 6

Some materials produce invisible radiation, consisting of charged particles

Question 7

What did Marie and Pierre Curie discover?

Answer 7

radiation consisted of small particles

Question 8

Radioactivity:

Answer 8

Spontaneous emission of high energy radiation and particles

Question 9

beta particles

Answer 9

high energy electrons

Question 10

alpha particles

Answer 10

+2 charge

Question 11

What did Ernest Rutherford do?

Answer 11

bombarded a thin gold foil with alpha particles to test the plum pudding model

Question 12

What did James Chadwick do?

Answer 12

bombarded a thin sheet of beryllium with alpha particles and radiation was not deflected.

Question 13

what did James Chadwick discover?

Answer 13

Neutrons

Question 14

What did Francis Aston’s Positive Ray Analyzer do?

Answer 14

Neon gas ions of different masses strike the detector in different locations.

Question 15

what were the results of the positive ray analyzer?

Answer 15

two different kinds of neon gas atoms exist: 90% is 20 amu; 10% is 22 amu

Question 16

Isotopes

Answer 16

atoms of an element containing the same number of protons but different number of neutrons

Question 17

Isotope symbol: Mass number

Answer 17

A: total number of nucleons in the nucleus

Question 18

elemental symbol

Answer 18

one or two letter symbols to identify the type of atom

Question 19

atomic number

Answer 19

Z; the number of protons only in the nucleus; identifies the element

Question 20

average atomic mass

Answer 20

weighted average of the masses of all isotopes of an element

Question 21

natural abundance

Answer 21

how much of each isotope is in a natural sample

Question 22

What did Dmitri Mendeleev do?

Answer 22

ordered elements by atomic mass, columns based on chemical and physical properties, and left open spaces for elements undiscovered.

Question 23

How is the periodic table organized?

Answer 23

horizontal rows are periods, vertical columns are groups

Question 24

What categories are elements on periodic table divided into?

Answer 24

metals - left and bottom
non metals - right and top
metalloids - between metals and nonmetals

Question 25

what are the groups of elements?

Answer 25

alkali metals, alkaline earth metals, halogens, noble gases

Question 26

molecular compounds

Answer 26

atoms held together by covalent bonds

Question 27

covalent bond

Answer 27

bond between two atoms created by sharing one or more pairs of electrons

Question 28

what are molecular compounds composed of?

Answer 28

nonmetals

Question 29

molecular formula

Answer 29

shows the number and type of atoms present in one molecule of a compound

Question 30

empirical formula

Answer 30

smallest whole number ratio of elements in a compound

Question 31

ionic compounds

Answer 31

consist of ions that formed due to the complete transfer of electrons.

Question 32

what are ionic compounds made of?

Answer 32

a metal and a nonmetal

Question 33

do metals and nonmetals for cations or anions?

Answer 33

metals form cations; nonmetals form anions

Question 34

what are molecular compounds formed of?

Answer 34

nonmetals

Question 35

how are molecular compounds named?

Answer 35

first words is the first element in the formula. second word is the second element with modified suffix. use prefixes to indicate number of atoms of each element. sulfur trioxide