Atomic Theory

Question 1

What is the fundamental unit of matter?

Answer 1

Atom

Question 2

Who proposed the first modern atomic theory?

Answer 2

John Dalton

Question 3

True or False: Aristotle believed that matter was composed of indivisible atoms.

Answer 3

False

Question 4

What did J.J. Thomson discover?

Answer 4

The electron

Question 5

Fill in the blank: The nucleus of an atom contains ______ and ______.

Answer 5

protons, neutrons

Question 6

Who is known for the gold foil experiment?

Answer 6

Ernest Rutherford

Question 7

What did Rutherford conclude about the structure of the atom?

Answer 7

Atoms have a small, dense nucleus surrounded by electrons.

Question 8

What is the charge of a proton?

Answer 8

Positive

Question 9

What is the charge of an electron?

Answer 9

Negative

Question 10

True or False: Dalton’s atomic theory stated that all atoms of a given element are identical.

Answer 10

True

Question 11

Which scientist introduced the concept of the ‘plum pudding model’?

Answer 11

J.J. Thomson

Question 12

What is the relative mass of a neutron compared to a proton?

Answer 12

Approximately equal

Question 13

What is density defined as?

Answer 13

Mass per unit volume

Question 14

Fill in the blank: The atomic number of an element is determined by the number of ______ in its nucleus.

Answer 14

protons

Question 15

Who proposed that matter is made up of four elements: earth, water, air, and fire?

Answer 15

Aristotle

Question 16

What is the mass of an electron compared to a proton?

Answer 16

Much smaller

Question 17

Multiple choice: Which of the following scientists is associated with the planetary model of the atom? A) Dalton B) Thomson C) Rutherford D) Bohr

Answer 17

C) Rutherford

Question 18

What does the term ‘isotope’ refer to?

Answer 18

Atoms of the same element with different numbers of neutrons.

Question 19

True or False: The atomic mass of an element is the weighted average of the masses of its isotopes.

Answer 19

True

Question 20

What is the main limitation of Dalton’s atomic theory?

Answer 20

It does not account for isotopes.

Question 21

Fill in the blank: The electron cloud model describes the ______ of electrons around the nucleus.

Answer 21

probability distribution

Question 22

Who is credited with the discovery of the neutron?

Answer 22

James Chadwick

Question 23

What is the significance of the mass number?

Answer 23

It indicates the total number of protons and neutrons in an atom.

Question 24

Multiple choice: Which particle has the least mass? A) Proton B) Neutron C) Electron D) Alpha particle

Answer 24

C) Electron

Question 25

True or False: The density of an object can change with temperature and pressure.

Answer 25

True

Question 26

What is the term for the center of an atom?

Answer 26

Nucleus

Question 28

What is the Law of Multiple Proportions?

Answer 28

When two elements can combine to form more than one compound, the ratios of the masses of one element that combine with a fixed mass of the other element are in small whole number ratios.

Question 29

True or False: The Law of Definite Proportions states that a chemical compound always contains its component elements in fixed ratios by mass.

Answer 29

True

Question 30

Fill in the blank: The Law of __________ Proportions states that a compound is always composed of the same elements in the same proportion by mass.

Answer 30

Definite

Question 31

Which law explains why water (H2O) always contains 2 hydrogen atoms for every oxygen atom?

Answer 31

Law of Definite Proportions

Question 32

Provide an example of the Law of Multiple Proportions.

Answer 32

Carbon monoxide (CO) and carbon dioxide (CO2) are examples where carbon and oxygen combine in different ratios.

Question 33

What does the Law of Definite Proportions imply about the composition of a compound?

Answer 33

It implies that the composition of a compound is constant regardless of its source.

Question 34

True or False: The Law of Multiple Proportions can be applied to ionic compounds only.

Answer 34

False

Question 35

What is the ratio of masses in the Law of Multiple Proportions?

Answer 35

The ratio is expressed in small whole numbers.

Question 36

Which scientist is primarily associated with the formulation of the Law of Definite Proportions?

Answer 36

Joseph Proust

Question 37

In the context of the Law of Multiple Proportions, what does it mean when two compounds are formed from the same elements?

Answer 37

It means they can combine in different ratios to form different compounds.

Question 38

Give an example of two elements that illustrate the Law of Multiple Proportions.

Answer 38

Nitrogen and oxygen can form NO and NO2.

Question 39

True or False: The Law of Definite Proportions applies to mixtures.

Answer 39

False

Question 40

What is the significance of the Law of Multiple Proportions in chemistry?

Answer 40

It helps to understand the ratios in which elements combine to form different compounds.

Question 41

Fill in the blank: The Law of Multiple Proportions is a fundamental principle that supports the __________ theory of matter.

Answer 41

atomic

Question 42

What type of ratio does the Law of Definite Proportions describe?

Answer 42

Fixed ratio by mass of constituent elements.

Question 43

Which law can be used to predict the possible compounds formed by two elements?

Answer 43

Law of Multiple Proportions

Question 44

True or False: The Law of Definite Proportions is applicable to all chemical compounds.

Answer 44

True

Question 45

When two elements form multiple compounds, what do the mass ratios of those compounds represent?

Answer 45

Small whole number ratios.

Question 46

What is a common misconception about the Law of Definite Proportions?

Answer 46

That it applies to variable compositions, such as mixtures.

Question 47

Which law would you reference to explain why NaCl always contains sodium and chlorine in a 1:1 ratio?

Answer 47

Law of Definite Proportions

Question 48

What is the relationship between the Law of Multiple Proportions and atomic theory?

Answer 48

It supports the idea that matter is made of discrete atoms combining in whole number ratios.

Question 49

Fill in the blank: The Law of __________ Proportions is essential for stoichiometry in chemical reactions.

Answer 49

Definite

Question 50

How do the Laws of Multiple and Definite Proportions relate to the concept of conservation of mass?

Answer 50

Both laws imply that mass is conserved in chemical reactions and that elements combine in fixed ratios.

Question 51

What happens when the ratios of elements do not conform to the Law of Definite Proportions?

Answer 51

It indicates that the substances are not pure compounds.