CHM 1045 Unit 1 Exam - Dillon

Chemistry is...

the study of matter

Matter is...

anything that takes up space and has mass

Physical properties =

are those which can be observed without changing the substance into something else

Chemical properties =

are those which are observed by changing one substance into another

Hypothesis :

an educated guess about the relationship between independent and dependent variables

Independent variable :

is a factor that's intentionally varied by the experimenter

Dependent variable:

is the factor that may change as a result of changes made in the independent variable

In a scientific experiment, the _____ is the group that serves as the standard of comparison; may be "no treatment" or an "experimenter selected" group

Control

_____ in an experiment are all the factors that the experimenter attempts to keep the same

Constant

___ are forms of matter

Substances

All matter is composed of _____

molecules

All molecules are composed of _____

Atoms

All atoms are composed of ______, _____, + ______

protons, neutrons, + electrons

color, melting point, boiling point, density, electrical conductivity

examples of physical properties

reactivity with water, flammability, decomposition products upon heating

examples of chemical properties

Pure substance:

matter having an invariant chemical composition + distinct properties

Pure substances can be _____ or ______

elements, compounds

Elements:

fundamental substances; can not be separated into simpler substances by chemical methods

example: iron metal (Fe)

compound:

substance composed of 2 or more elements in fixed proportions; can be separated into simpler substances and elements only by chemical methods

example: table salt (NaCl)

mixture:

matter consisting of 2 or more pure substances that retain their individual identities + can be separated by physical methods

Matter occurs in nature as a ______ or ______

pure substance, mixture

Mixtures can be _____ or ______

homogenous, heterogeneous

Homogenous:

mixture in uniform (solution)

example: apple juice

Heterogenous:

mixture not uniform (can be separated)

example: salad dressing

Mixtures ______ be separated, but solutions _____ be.

can, can not

Diatomic:

2 atoms together

Polyatomic:

many atoms together

H2, N2, O2, F2, CL2, BR2, I2

diatomic molecules

P4, S8

polyatomic molecules

For a solid to change to a liquid, we have to add heat + call the process _____

melting

For a solid to change to a gas, we have to lower the pressure significantly + call the process ______

sublimation

For a liquid to change to a solid, we have to reduce the temperature + call the process ______

freezing

To change a liquid to a gas, we have to add heat + call this process ____

vaporization

To change a gas to a liquid, we need to either increase the pressure or cool the temperature, or both. This is what makes rain and is called ______

condensation

To change a gas to a liquid, we have to increase the pressure a lot while maintaining the temperature, and call this process _____

deposition

Four states of matter:

solids, liquids, gases, plasmas

5th state of matter:

Bose-Einstein Condensate

Density =

mass / volume

Density is....

how closely packed together a substance is

reduce volume = _____ dense

more

increase mass = ____ dense

more

How did king henry die?

King Henry Died By Drinking Chocolate Milk

When finding the sig figs from addition and subtraction, count the number of sig figs in the ______ portion for each number in the problem. Then, round answer to least number of sig figs from problem.

decimal

When finding the sig figs from multiplication and division, count the _____ number of sig figs in ____ number of problem determines the # of sig figs in answer.

least, any

Relative uncertainty =

absolute error / measured value

Bohr Model :

model with nucleus orbited by electrons, which are different in energy levels

Democritus :

Matter could not be divided into smaller and smaller pieces forever, eventually the smallest possible piece would be obtained, and the piece would be invisible.

Aristotle and Plato:

Believed nature of matter was made of 4 elements (earth, fire, air and water)

Dalton's Atomic Theory

1) elements are composed of atoms. 2) atoms of same element are identical, but differ from other elements. 3) elements can mix together 4) atoms only change when mixed with other elements

Thomson

Plum pudding model; atoms were made from a positively charged substance with negatively charged electrons scattered about

Rutherford's Gold Foil experiment

proposed that atoms consist of a tiny, massive, positive nucleus surrounded by electrons

Wave Model

current model of the atom, based on wave mechanics; electrons do not move about an atom in a definite path; probable location of an electron is based on how much energy the electron has

Electron cloud

a region around the nucleus of an atom where electrons are likely to be found

Atom:

smallest unit of matter that retains the identity of the substance

Atoms are composed of 2 regions: ____ + ___

nucleus, electron cloud

Nucleus contains 2 of 3 subatomic particles:

protons + neutrons

Protons :

much larger and heavier than electrons, have a positive charge

mass = 1.67262158x10^-27 kg

Neutrons:

are slightly larger and heavier than protons, have no electrical charge

mass = 1.67492716x10^-27 kg

Electron cloud contains 3rd subatomic particle outside of nucleus:

electrons

electrons:

tiny, very light particles that have a negative charge

mass = 9.10938188x10^-31 kg

In neutral atoms...

# of protons = # of ____

electrons

Atomic number indicates the # of ___ in an atom

protons

# of neutrons + # of protons =

mass number

Ions are...

an element whoses protons do not equal electrons

# of protons - # of electrons =

charge of element

_____ charge = # of protons > # electrons

positive

______ charge = # protons < # electrons

negative

isotopes:

atoms of same element can have different #'s of neutrons; the different possible versions of each element are called isotopes

Law of conservation of mass:

the total mass of starting material = total mass of product

Mass is ...

neither created nor destroyed

____ _____ provides information about percentages of different isotopes of each element

Mass spectrometer

Periodic table mass is the weighted ____ of all of the ____ of each element

average, isotopes

Steps to finding average atomic mass:

1. convert each % into decimals

2. multiply mass of each isotope by corresponding decimal value

3. add contributions together

Law of definite proportions:

states that different samples of a given compound always contain the same elements in the same mass ratio

Law of multiple proportions:

states that if 2 elements can combine to form more than one compound with each other, the masses of one element that combine with a fixed mass of the other element are in ratios of small whole numbers

molecule:

combination of at least 2 atoms in a specific arrangement held together by chemical bonds

- can be an element or compound

diatomic molecules:

are either homonuclear (2 of the same atom) or heteronuclear (2 different atoms)

homonuclear diatomic molecules:

H2, N2, O2, F2, Cl2, Br2, I2

Heteronuclear diatomic molecules:

CO, HCl

Polyatomic molecules:

- contain more than 2 atoms

- most molecules

- may contain more than one element

- examples: water H20, methane CH4

Allotrope:

one of 2 or more distinct forms of an element

examples: oxygen O2 + ozone O3; diamond + graphite (forms of carbon)

Empirical formula:

describes the ratio of atoms in a molecule; this means the representation shows the lowest whole number ratio of the atoms in a molecule

isomer

different orientations atoms can take in molecules with exactly the same number and ratio of atoms

spatial or geometric isomer:

the attachments look very similar but vary by how much they are attached in space

Mendeleev:

first to publish a periodic table

Mercury + Bromine =

2 naturally occurring liquids

Periods:

rows in the periodic table; are separated by the way the electrons around an atom fill

Groups:

columns

Group 1:

Alkali Metals

Group 2:

Alkaline Metals

Group 3-12:

Transition Metals

Groups 13 + 14:

Metalloids

Group 15:

Pnictogen group

Group 16:

Chalcogen group

Group 17:

Halogen group

Group 18:

Noble Gas Group

2 extra rows on periodic table:

Lanthanides + Actinides

ions form ____ based on where they are on the table.

naturally

Alkaline metals form ___ ions

+1

Group 2 forms ___ ions

+2