Atoms

Question 1

What is matter?

Answer 1

anything that has mass and occupies space

Question 2

What is matter composed of?

Answer 2

particles

Question 3

What dictates the properties of matter?

Answer 3

how particles come together

Question 4

what is chemistry?

Answer 4

the discipline that seeks to understand matter and its properties.

Question 5

how can matter be classified?

Answer 5

by state and composition.

Question 6

what are the different states?

Answer 6

solid, liquid or gas.

Question 7

what does composition mean>

Answer 7

the types of particles that form it.

Question 8

How does a state of matter change from solid to liquid?

Answer 8

By increasing temperature.

Question 9

What is solid matter?

Answer 9

how atoms or molecules pack closely to each other in fixed locations.

Question 10

What does a solid have fixed?

Answer 10

the volume and rigid shape.

Question 11

what is liquid matter?

Answer 11

atoms or molecules pack about as closely as they do in solid matter, but they are free to move relative to each other.

Question 12

what does liquids have fixed?

Answer 12

volume but not a fixed shape.

Question 13

what is gaseous matter>

Answer 13

atoms or molecules that have a lot of space between them and are free to move relative to one another.

Question 14

what qualities make a gaseous matter?

Answer 14

gases are compressible.

Question 15

what is a pure substance?

Answer 15

it is made up of only one component and the composition is invariant.

Question 16

what is a mixture?

Answer 16

a substance composed of two or more components in proportions that can vary from one sample to another.

Question 17

how are pure substances categorized?

Answer 17

elements and compounds.

Question 18

what is an element?

Answer 18

a substance that cannot be chemically broken down into simpler substances.

Question 19

what is a compound?

Answer 19

substance composed of two or more elements in fixed definite proportions.

Question 20

how can mixtures be categorized?

Answer 20

heterogeneous and homogeneous

Question 21

what is a heterogeneous mixture?

Answer 21

the composition varies from one region of the mixture to another.

Question 22

what is a homogenous mixture?

Answer 22

is made of multiple substances, composition is the same throughout the whole sample.

Question 23

who were the first to propose that matter was composed of small, indestructible particles called “Atomos”?

Answer 23

Democritus and Leucippus.

Question 24

who proposed that different substances were composed of various proportions of fire, air, earth, and water?

Answer 24

Plato and Aristotle.

Question 25

what is the law of conservation of mass?

Answer 25

In a chemical reaction matter is neither created nor destroyed, it’s transformed.

Question 26

what is the law of definite proportions.

Answer 26

all samples of a given compound, regardless of their source or how they were prepared, have the same proportions of their constituent elements.

Question 27

what is the law of multiple proportions?

Answer 27

the ratio of these two masses is itself a small whole number

Question 28

who discovered the electron?

Answer 28

J.J Thomson

Question 29

what is an electron?

Answer 29

a low-mass particle present within all atoms.

Question 30

what charge does an electron have?

Answer 30

-1

Question 31

who and in which experiment deduced the charge of a single electron?

Answer 31

Millikan’s oil drop experiment.

Question 32

What did J.J Thomson proposed?

Answer 32

that negatively charged electrons were small particles held within a positively charged sphere., also known as the plum-pudding model.

Question 33

what does the gold foil experiment consist of>

Answer 33

Rutherford directed positively charged particles at an ultra thin sheet of gold foil.

Question 34

what did Rutherford’s experiment show?

Answer 34

Matter must not be as uniform as it appears, it must contain large regions of empty space dotted with small regions of very dense matter.

Question 35

who has nearly identical masses?

Answer 35

protons and neutrons.

Question 36

how is the identity of an atom determined?

Answer 36

by the number of protons in its nucleus, the number of protons define the element.

Question 37

what do atoms of a given element have the same number but vary differently?

Answer 37

elements have the same number of protons but they do not necessarily have the same number of neutrons.

Question 38

what is an isotope>

Answer 38

atoms with the same number of protons but a different number of neutrons.

Question 39

what is the mass number?

Answer 39

the sum of the number of neutrons and protons in an atom

Question 40

what is natural abundance?

Answer 40

the percentages of the isotope.

Question 41

how is atomic mass also known>

Answer 41

as atomic weight or standard atomic weight.

Question 42

what does the atomic mass of an element represent?

Answer 42

the average mass of the isotope that compose that element, it is a weighted value based on the element natural abundance of each isotope.

Question 43

what is the formula for atomic mass?

Answer 43

isotopic mass (fractional abundance of isotope.)

Question 44

what is mass spectrometry?

Answer 44

the masses of atoms and the percent abundances of isotopes of elements, this technique separates particles according to their mass.

Question 45

mole

Answer 45

mass in grams of one element equivalent to its atomic weight

Question 46

Avogadro’s Number

Answer 46

One mole of any element contains 6.022*10^23 atoms

Question 47

what is a mole of substance?

Answer 47

number of gram is equal to the atomic/molecular weight of that substance.

Question 48

what is molar mass?

Answer 48

the mass of 1 mol of atoms of an element.

Question 49

what is numerically equal to the element atomic mass in atomic mass units?

Answer 49

an element molar mass in grams per mole.