Dalton's Atomic Theory

Question 1

According to law of mass

conservation: the total mass of substances does not change during a chemical reaction. What does it mean?

Answer 1

The number of substances may change and, by definition, their properties
must, but the total amount of matter remains constant. This means that atoms are neither created nor destroyed

Question 2

State the law of mass conservation

Answer 2

The total mass (of substances) remains constant during a chemical reaction

Question 3

According to the law of definite

(or constant) composition, no matter what its source, a particular * is composed of the same * in the same * by mass.

Answer 3

compound, elements, parts ((fractions))

Question 4

State the law of definite composition

Answer 4

Any sample of a given compound has the same elements present in the same parts by mass

Question 5

law of multiple proportions:
if elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as *

Answer 5

a ratio of small whole numbers.

Question 6

State the law of multiple proportions

Answer 6

in different compounds of the same
elements, the masses of one element that combine with a fixed mass of the other
can be expressed as a ratio of small whole numbers.

Question 7

Who proposed the law of mass conservation?

Answer 7

Antoine Lavoisier

Question 8

Dalton’s atomic theory

1. All matter consists of atoms, tiny indivisible particles

Answer 8

pass

Question 9

2. All atoms of a given element are the identical but different from atoms of all other elements

Answer 9

pass

Question 10

3. Atoms of one element cannot be converted to atoms of another element

Answer 10

atoms of the original substances recombine to form different substances and thus atoms are neither created nor destroyed in a chemical reaction.

Question 11

4. Compounds result from the chemical combination of a specific ratio of atoms of different elements

Answer 11

pass

Question 12

In the cathode ray experiment, what observations led to the discovery of electrons?

Answer 12

Cathode rays bent in magnetic field and towards the positive plate in ef

Question 13

What is the main conclusion in the cathode ray experiment?

Answer 13

cathode rays consist of negatively charged particles found in all matter.

Question 14

What does J.J. Thomson discover about the electron?

Answer 14

The mass/charge ratio

Question 15

Who discovers the charge of electron? mass?

Answer 15

Robert Millikan

Question 16

What is the name of the experiment performed by Robert Millikan?

Answer 16

Oil drop experiment

Question 17

What does Ernest Rutherford discover?

Answer 17

Ernest Rutherford proposed that atoms consist of a tiny, massive, positive nucleus
surrounded by electrons. He proposed that positive particles lay within the nucleus and called them protons.

Question 18

• (1891–1974) discovered the neutron, an uncharged dense particle that also resides in
  the nucleus.

Answer 18

James Chadwick

Question 19

The atomic mass unit or * is a unit of relative
mass, but it has an absolute
mass of 1.660543* 10^-24 g.

Answer 19

Dalton

Question 20

Thus, the atomic mass unit (amu) is * the mass of a carbon-12 atom.

Answer 20

1/12

Question 21

The mass of an atom is measured * to the mass of an *. The modern standard is the *, whose mass is defined as exactly 12 atomic
mass units.

Answer 21

relative, atomic standard

carbon-12 atom