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2024-2025 > chemistry midterm > Flashcards

chemistry midterm Flashcards

1
Q

element

A

the simplest form of matter that has a unique set of properties and cannot be broken down further

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2
Q

compound

A

a substance that contains two or more elements chemically combined in a fixed proportion

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3
Q

mixture

A

a physical blend of two or more components (i.e. 2+ elements, 2+ compounds, or element(s) + compound(s))

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4
Q

homogeneous mixtures

A

-uniform throughout
-must be in a single phase
-may seem like one thing
-can’t see the different substances
-can’t see the particles
-can be separated by physical means

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5
Q

heterogeneous mixtures

A

-not uniform throughout
-can be in more than one phase
-can see the different parts
-can be separated by physical means

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6
Q

why can mixtures be separated by physical means?

A

differences in physical properties can be used to separate components in a mixture

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7
Q

what are the ways that mixtures can be separated by physical means?

A

magnetism, evaporation/boiling, separation by hand, decanting or separation funnel, filtration, and distillation

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8
Q

magnetism

A

difference in magnetic properties (ex. iron + aluminum nails)
-IRON IS MAGNENTIC

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9
Q

evaporation/boiling

A

difference in boiling points (ex. salt water)

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10
Q

separation by hand

A

difference in color/physical appearance (ex. m&ms)

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11
Q

decanting or separation funnel

A

distinct layers due to different densities/polarities (ex. oil + water)

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12
Q

filtration

A

difference in particle size (ex. pepper + water)

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13
Q

distillation

A

differences in boiling points (ex. top water or window wiping fluid)

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14
Q

explain that compounds can only be separated into elements by chemical means

A

the elements within a compound are held together by chemical bonds, which can only be broken through a chemical reaction

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15
Q

give example of compounds being separated into elements by chemical means

A

water (H2O) which can be broken down into hydrogen and oxygen through electrolysis, mercuric oxide (HgO) which decomposes into mercury and oxygen when heated, and calcium carbonate (CaCO3) which can be separated into calcium oxide and carbon dioxide through thermal decomposition

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16
Q

intensive properties

A

properties that do not depend on the amount of matter
does not depend on amount but on TYPE

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17
Q

types of intensive properties

A

color, melting + boiling points, and density (mass/volume)

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18
Q

extensive properties

A

properties that depend on the AMOUNT of matter

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19
Q

types of extensive properties

A

mass, volume, and energy

20
Q

physical properties

A

properties that can be observed or measured without changing the composition/identity of a substance (i.e. without performing a chemical reaction)

21
Q

physical properties examples

A

color, mass, volume, melting/boiling point

22
Q

chemical properties

A

properties that can only be observed by changing the composition/identity of
a substance (such as in a chemical reaction when atoms are rearranged, and new substances are
formed)

23
Q

chemical properties examples

A

flammability, reactivity, toxicity, and acidity

24
Q

physical change

A

a change that alters some property of the substance, such as form or appearance. the identity/composition of the substance remains the same. no new substance is formed.

25
Q

two types of physical changes

A

irreversible and reversible

26
Q

irreversible physical changes

A

breaking, tearing, cutting, grinding, etc

27
Q

reversible physical changes

A

all phase changes

28
Q

phase changes

A

drawing on notes

29
Q

chemical changes

A

during a chemical reaction, a chemical change occurs, which changes the identify
of a substance
A NEW SUBSTANCE IS FORMED

30
Q

indicators of a chemical change

A

change in color, transfer of energy (change in temp- hotter or colder; heat/fire, etc.), production of a gas (bubbling, fizzing, odor, sound), and formation of a precipitate (ppt)

31
Q

state the law of conservation of matter during chemical reactions

A

mass cannot be created nor destroyed
-mass is always conserved during a chemical reaction
-total mass of the reactants must equal the total mass of the products

32
Q

how do physical/chemical properties differ from physical/chemical changes?

A

properties: measured or observed characteristics (adjectives)
changes: alter physical properties or chemical identities (verbs)

BIG DIFFERENCE: DOES THE COMPOSITION CHANGE OR NOT?

33
Q

3 types of subatomic particles

A

proton, electron, neutron

34
Q

electric charge, symbol, location in atom, mass in grams, and mass number for proton

A

electric charge: 1+
symbol: p+
location: nucleus
mass in grams: 1.67 × 10^-24 g
mass number: 1

35
Q

electric charge, symbol, location in atom, mass in grams, and mass number for electron

A

electric charge: 1-
symbol: e-
location: outside the nucleus/in the electron cloud
mass in grams: 9.12x 10^-28g
mass number: 0

36
Q

electric charge, symbol, location in atom, mass in grams, and mass number for neutron

A

electric charge: 0
symbol: n^0
location in atom: nucleus
mass in grams 1.67x10^-24g
mass number: 1

37
Q

how do you determine the number of each type of subatomic particle using the chemical symbol, isotope symbol, ion charge, and/or periodic table

A

use the element’s atomic number (found on the periodic table) to find the number of protons, which is then equal to the number of electrons in a neutral atom; the mass number (part of the isotope symbol) is used to calculate the number of neutrons by subtracting the atomic number from the mass number; and the ion charge indicates how many electrons have been gained or lost compared to a neutral atom

38
Q

isotope

A

-isotopes of the same element have different mass numbers because they have different numbers of neutrons
-they show the same chemical properties because a difference in the number of neutrons makes no difference to how atoms react

39
Q

how does an isotope occur

A

spontaneously through radioactive decay of a nucleus or artificially by bombarding a stable nucleus with charged particles via accelerators or neutrons in a nuclear reactor

40
Q

two types of isotopes

A

stable isotopes and radioisotopes

41
Q

stable isotopes

A

stability depends on the balance between the number of protons and neutrons

42
Q

radioisotopes

A

isotopes that have unstable nuclei and become more stable through nuclear reactions

43
Q

explain how the weighted average atomic mass of an element is determined

A

multiplying the relative abundance of each naturally occurring isotope of that element by its atomic mass, then adding up all those products; essentially, this means the more abundant an isotope is, the greater its contribution to the overall average atomic mass of the element

44
Q

average atomic mass formula

A

(mass x %abundance)↓1 + (mass x %abundance)↓2 +…/100%

unit: amu or g
round to: the hundredths place

45
Q
A

2024-2025 (10 decks)

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