Unit 1 Flashcards

1
Q

Chemical change

A

When the chemical composition of a substance is altered and results in new substances being formed

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2
Q

Chemical reaction

A

The conversion of two or more elements to a chemical compund

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3
Q

Compound

A

Contains two or more elements and has chemical and physical properties that are usually different from those of the elements of which it is composed.

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4
Q

Distillation

A

Physical process of converting homogenous mixtures

The mixture is boiled, and the most volatile substance is boiled first, and then it is condensed back into a liquid in the recieving flask, while the less volatile component remains in the distillation flask

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5
Q

Electrolysis

A

Process of using electricity to separate water into hydrogen and oxygen

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6
Q

Elements

A

substance that cannot be broken down into simpler ones by chemical changes

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7
Q

Experiments

A

Systematic observations or measurments, usually under controlled conditions in which a single variable changes.

Enables scientist to determine whether the hypothesis is valid, incorrect or must be modified

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8
Q

Filtration

A

Method of separating heterogenous mixtures, where the mixture is passed through barrier, with holes or pores smaller than the solid particles.

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9
Q

Gases characteristics

A

Have neither fixed shapes or volumes and expand to fill their container

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10
Q

Heterogenous mixtures

A

When composition of a material is not completely uniform, or their component parts cannot be easily separated.

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11
Q

Homogenous (or solutions)

A

Materials that are in the same state, have no visible boundries, and are uniform throughout.

Ex. air and tap water

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12
Q

How are homogenous mixtures separated?

A

Through physical processes called distillation and crystallization

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13
Q

How can kinetic energy of a substance be changed?

A

Through heating and cooling, which can change the physical state of a substance

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14
Q

Hypothesis

A

Educated guess that puts scientist’s understanding of the topic into a form that can be tested

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15
Q

Intermolecular forces

A

Attractive forces that try to draw particles in

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16
Q

John Dalton’s atomic theory

A

Fundamental concept that states all elements are composed of atoms

Postulates of the theory was
1. All matter is composed of extremely small particles called atoms.
2. Atoms of a given element are identical in size, mass, and other properties.
3. Atoms of different elements differ in size, mass, and other properties.
4. Atoms cannot be subdivided, created, or destroyed.
5. Atoms of different elements can combine in simple whole number ratios to form chemical compounds.
6. In chemical reactions, atoms are combined, separated, or rearranged.

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17
Q

Kinetic energy

A

Function of substance temperature that keeps molecules apart and moving around

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18
Q

Law

A

Verbal or mathematical description of phenomenon that says what happens but not why it happens

Allows for general predictions

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19
Q

Law of Conservation

A

States that in a chemical reaction, matter is neither created, nor destroyed but remains constant in the system

Total mass of reactants = Total mass of products

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20
Q

Law of definite proportions

A

a given chemical compound always contains its component elements in fixed ratio (by mass) and does not depend on its source and method of preparation.

Applies when elements are reacted together to form the same product, thus can be used to compare to experiments where elements react to form the same compound.

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21
Q

Laws of chemical combination

A

Foundational laws that describe how substances react

  1. Law of Conservation of Mass
  2. Law of Definite Proportions
  3. Law of Multiple Proportions
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22
Q

Liquid characteristics

A

have fixed volumes but flow to assume the shape of their containers

23
Q

Physical change

A

Process of matter changing from one physical state to another

24
Q

Pressure

A

Amount of force exerted on a given area

25
Q

Pure chemical substance

A

Any matter that has a fixed chemical composition and characteristic properties

ex. Oxygen since it is a pure colorless, oderless gas at 25 C

26
Q

Qualitative observations

A

Describe properties or occurances in ways that do not rely on numbers

ex: table salt is a crystalline solid, sulfur crystals are yellow

27
Q

Scientific method

A

How scientists search for answers to questions and solutions to problems

  1. Making observations
  2. Formulating hypothesis
  3. Designing experiments
28
Q

Solid characteristics

A

Relatively rigid and have fixed shapes and volumes

29
Q

Theory

A

Thought-out explanation of the natural world, constructed using the scientific method

30
Q

Three common states of matter

A

Solid, liquid and gas

31
Q

What can most mixtures be broken down into?

A

Pure substances, which could be either elements or compounds

32
Q

What does the state of a substance depend on?

A

The balance between kinetic energy of individual particles and intermolecular forces

33
Q

What is the volume of gases dependent on?

A

Temperature and pressure

34
Q

What would affect intermolecular forces?

A

Increasing the pressure on a substance would force molecules closer together, thus increasing IM forces

35
Q

Electrostatic forces

A

The electric charge two objects exert on each other

36
Q

What is the magnitude of the force dependent on?

A

It is linearly proportional to the distance between the two objects

Inversely proportional to the square distance between each other

37
Q

Elementary charge

A

Charge of electron and donated by e

Fundamental physical constant that is 1.602176634× 10^−19 C

38
Q

Electron

A

Negatively charged sub-atomic particle that is either bound to an atom or free

39
Q

Thompson’s Non-nuclear model

A

Thomson’s model that electrons were embedded in a uniform sphere that contained both the positive charge and most of the mass in an atom.

Was created around the conclusion that atoms must have positive charges to balance the negative ones.

40
Q

Ernest Rutherford experiments

A

Passed a beam of alpha positive particles through a gold foil that contained atoms.

Concluded most atom was empty space since many particles went straight through

Concluded a very dense positive charged nucleus since some particles were deflected

41
Q

Protons

A

Positively charged particles

42
Q

Properties of subatomic particles

A
  1. Electrions have electrical charges identical in magnitude but opposite in sign. Charge of proton is +1 and charge of electron is -1
  2. Neutrons have approximately the same mass as protons but no charge, electrically neutral
  3. The mass of a proton or a neutral is about 1836 times greater than the mass of an electron. Protons and neutrons make a bulk of the atom mass
43
Q

Structure of atom

A

Almost all atom mass contained in tiny dense nucleus that carries a positive electric charge.

Almost all atom volume consists of empty space where electrons reside

44
Q

Strong nuclear forces

A

Electrostatic repulsions between negatively charged electrons would cause the electrons to be uniformly distributed
throughout the atom’s volume.

Stronger than electrostatic interactions and holds the nucleus together

45
Q

Atomic number (Z)

A

Defining trait of element that determines identity

Number of protons in nucleus of atom

Also indicates number of electrons in a neutral atom

46
Q

Mass number (A)

A

Total # of protons and neutrons in an atom

47
Q

How to find the number of neutrons

A

Find difference between mass number and atomic number

A - Z = # of neutrons

48
Q

Periodic table

A

Table of known elements arranged in order of increasing Z

49
Q

What is the chemistry of each elements determined by?

A

Their # of protons and electrons

50
Q

Isotopes

A

Elements that have the same number of protons but different numbers of neutrons

All isotopes exhibit the same chemistry and only differ in mass number

51
Q

Ion

A

Atoms that contain different number of protons and neutrons

Electrically charged and is defined by its atomic charge

Atomic charge = # of protons - # of electrons

52
Q

Atomic mass

A

Weighted average mass of all naturally occurring isotopes of the element

53
Q

How are the relative masses of atoms reported?

A

Atomic mass unit (amu)