THE ATOM

Question 1

postulated that all matter is made up of small, indestructible units called atoms

Answer 1

Democritus 400BC

Question 2

proposed his atomic theory, such as
1. each element is made up of atoms
2. atoms of a given element are identical
3. compounds are formed when atoms combine with each other
4. chemical reactions involve the reorganization of the atoms

Answer 2

John Dalton

Question 3

created the periodic table and discovered that the properties of elements are periodic functions of their atomic weights

Answer 3

Dmitri Mendeleev

Question 4

proposed the tehory of electromagnetism and established the connection between light and electromagnetic waves

Answer 4

James Clerk Maxwell

Question 5

proposed that electricity is made up of discrete negative particles- electrons

Answer 5

George Stoney

Question 6

conducted experiments with cathode ray tubes, demonstrating that cathode rays carry a negative charge

Answer 6

Sir William Crookes

Question 7

ued cathode ray tubes to study canal rays, which have electrical and magnetic properties opposite to those of an electron

Answer 7

Eugene Godstein

Question 8

discovered that certain materials glowe when exosed to cathode rays and names these X-rays

Answer 8

Wilhelm Roentgen

Question 9

discovered radiation by studying the effects of uranium on photographic film

Answer 9

Henri Becquerel

Question 10

used cathode ray tubes to determine the charge-to-mass ratio of the electron

Answer 10

Sir Joseph John Thomson

Question 11

discovered alpha, beta, and gamma rays in radiation

Answer 11

Ernest Rutherford

Question 12

theorized that radioactive particles cause atoms to break down, releasing radiation in the form of energy and subatomic particles. they discovered the radioactive elements polonium and radium

Answer 12

pierre and marie curie

Question 13

proposed the idea of quantization to explain how a hot, glowing object emits light

Answer 13

Max Planck

Question 14

discovered that there appeared to be more than one element at certain positions on the periodic table.

Answer 14

Frederick Soddy

Question 15

the term “isotope” was coined by ______ as a suitable name of these elements

Answer 15

Margaret Todd

Question 16

discovered that noble gases have stable electorn configuration

Answer 16

Richard Abegg

Question 17

developed the theories of relativity and hypothesized about the particle nature of light

Answer 17

Albert Einstein

Question 18

invented a device capable of detecting alpha particles

Answer 18

Hans Geiger

Question 19

determined the charge of the electron through his oil drop experiment

Answer 19

RObert Millikan

Question 20

conducted the alpha particle experiment and established that the nucleus was very dense, very small, and positively charged

Answer 20

Ernest Rutherford

Question 21

developed the Bohr atomic model, which describes electrons traveling in orbits around the nucleus

Answer 21

Neils Bohr

Question 22

discovered that electrons exhibit wave-particle duality

Answer 22

Louis de Brglie

Question 23

developed the Schrodinger equation, which describes how the quantum state of a system changes over time

Answer 23

Erwin Schrodinger

Question 24

proposed the Law of Triads, which stated that the atomic weight of the middle element in certain triads was the average of the atomic weights of the other two elements

Answer 24

Johann Dobereiner

Question 25

proposed the Law of Octaves, which states that when elements are arranged by their atomic weight, every eighth element exhibits similar properties

Answer 25

John Newlands

Question 26

recognized the periodic behavior and repeating patterns among elements. studied the relationship between the atomic volume and the relative atomic mass of 28 elements

Answer 26

Lothar Meyer

Question 27

formulated periodic Law states that the elements' properties are periodic functions of their atomic masses. created a visionary version of the periodic table and used it to correct the properties of some already discovered elements varied with atomic number.

Answer 27

Dmitri Mendeleev

Question 28

discovered that the wavelengths of X-ray emissions from elements corresponded to their atomic number.

Answer 28

Henry Moseley

Question 28

TRUE or FALSE

Answer 28

with the discovery of isotopes, it became clear that atomic weight was less significant in the periodic law; instead, the properties of elements varied with atomic number.

Question 29

the number of protons is called and represented as

Answer 29

atomic number Z

Question 30

the total number of protons and neutrons in an atom is called the and represented as

Answer 30

mass number A

Question 31

electric charge of proton and electron

Answer 31

+1.6022x10^-19 -1.6022x10^-19

Question 32

mass of a proton

Answer 32

1.6726x10^-24 grams

Question 33

mass of a neutron

Answer 33

1.6749x10^-24 grams

Question 34

mass of an electron

Answer 34

9.1094x10^-28 grams

Question 35

are atoms of the same element that have the same number of protons (therefore the same chemical properties) but differ in the number of neutrons in their nuclei

Answer 35

isotopes

Question 36

is a tabular arrangement of the elements, organized by their atomic number, electron configurations, and recurring chemical properties

Answer 36

periodic table