Test 2

Question 1

Democritus

Answer 1

-460-370 BCE
-Proposed matter was not infinitely divisible
-Proposed atomos made up matter and couldn’t be created, destroyed, or divided and that they were homogeneous solids
Matter is composed of atoms, which move through empty space
-Different kinds of atoms have different shapes/sizes-that and their movement determine the properties of matter
-HIS IDEAS WERE AHEAD OF HIS TIME!!

Question 2

Aristotle

Answer 2

-384-322 BCE
-Empty space couldn’t exist
-Matter is made of earth, fire, air, and water
-Greek philosopher that rejected democritus’ ideas until 2000 years

Question 3

John Dalton

Answer 3

-1766-1844
-Dalton’s Atomic Theory:
-Matter is composed of extremely small particles called atoms
-Atoms are indivisible and indestructible
-Atoms of a given element are identical in size, mass, and chemical properties
-Atoms of a specific element are different from those of another element
-Different atoms combine in simple whole-number ratios to form compounds.
-In a chemical reaction, atoms are separated, combined or rearranged.

Question 4

Sir William Crookes

Answer 4

-Cathode ray: radiation from cathode to anode with zinc sulfide covering one end of the tube
-Stream of charged particles
-Carried a negative charge
-These negatively charged particles that are part of all forms of matter are known as electrons

Question 5

J.J. Thompson

Answer 5

-1856-1940
-Began a series of cathode-ray tube experiments at Cambridge to determine the ratio of the electron’s charge to its mass by measuring the effects of both magnetic and electric fields on a cathode ray
-1906 Nobel Prize
-Found electrons to be lighter than hydrogen, the lightest atom. So, he found electrons to be subatomic particles, proving Dalton wrong.
-Plum pudding model

Question 6

Robert Millikan

Answer 6

-1868-1953
-Determined charge of electron using oil-drop apparatus

Question 7

Ernest Rutherford

Answer 7

-1871-1937
-Studied how alpha particles (positively charged) interacted with solid matter
-Experiment: to see if alpha particles would be deflected as they passed through a thin gold foil
-Concluded an atom is mostly empty space through which electrons move and atom’s and charge and mass is almost all in the nucleus.
-A proton is a subatomic particle carrying a charge equal to but opposite that of an electron- 1+

Question 8

James Chadwick

Answer 8

-Rutherford’s coworker
-1891-1974
-Showed that the nucleus contained neutrons, subatomic particles with equal masses to protons, but with no electric charge
-Won the 1935 Nobel Prize.

Question 9

pure substance

Answer 9

only one element

Question 10

compound

Answer 10

a mixture of two or more elements that are chemically combined

Question 11

mixture

Answer 11

heterogeneous - a mixture in which the composition is not uniform throughout
homogeneous (solution) - a mixture in which the composition is the same throughout

Question 12

atom

Answer 12

makes up molecules, each atom is unique, pure substance, has protons, neutrons and electrons

Question 13

Filtration

Answer 13

uses a porous barrier to separate a solid from a liquid

Question 14

Distillation

Answer 14

based on differences in boiling points of the substances involved in a homogeneous mixture. A mixture is heated until the substance with the lowest boiling point is a vapor and then is collected condensed.

Question 15

Crystallization

Answer 15

a formation of pure solid particles from a solution containing a dissolved substance

Question 16

Sublimation

Answer 16

a solid change to vapor without melting/liquid phase. Used to separate two solids when they are sublimates and not the other

Question 17

Chromatography

Answer 17

separates the components of a mixture dissolved in either a gas or a liquid based on the ability of each component to travel or be drawn across the surface of a fixed substance. Components with the strongest attraction for the chromatography paper travel slower

Question 18

Law of multiple proportions

Answer 18

states that when different compounds have the same elements, different masses of one element combine with the same fixed mass of the other element in a ratio of small whole numbers.

(you’re finding the unit rate of the mass of two atoms in a compound and comparing it as a ratio to the mass of another compound by finding the unit rate between the two and expressing it as a ratio)

Question 19

Law of definite proportions

Answer 19

states that a compound is always composed of the same elements in the same proportion by mass, no matter how large/small the sample. The mass of the compound is equal to the sum of the masses of the elements that make up the compound. The relative amounts of the elements in a compound can be expressed as percent by mass-the ratio of the mass of each element to the total mass of the compound expressed as a percent.

Question 20

H20 is ALWAYS H20 because…

Answer 20

or else it’s a different compound-you can’t have half an oxygen atom

Question 21

Average atomic mass =

Answer 21

(atomic mass x % abundance in decimal form) + (atomic mass x % abundance in decimal form)