CHM 1045 Unit 1 Exam - Dillon
Law of conservation of mass:
the total mass of starting material = total mass of product
electrons:
tiny, very light particles that have a negative charge mass = 9.10938188x10^-31 kg
To change a liquid to a gas, we have to add heat + call this process ____
vaporization
Alkaline metals form ___ ions
+1
Group 2 forms ___ ions
+2
Group 1:
Alkali Metals
Group 2:
Alkaline Metals
Group 18:
Noble Gas Group
Electron cloud
a region around the nucleus of an atom where electrons are likely to be found
Relative uncertainty =
absolute error / measured value
Hypothesis :
an educated guess about the relationship between independent and dependent variables
Ions are...
an element whoses protons do not equal electrons
Matter is...
anything that takes up space and has mass
diatomic molecules:
are either homonuclear (2 of the same atom) or heteronuclear (2 different atoms)
Neutrons:
are slightly larger and heavier than protons, have no electrical charge mass = 1.67492716x10^-27 kg
Chemical properties =
are those which are observed by changing one substance into another
Physical properties =
are those which can be observed without changing the substance into something else
isotopes:
atoms of same element can have different #'s of neutrons; the different possible versions of each element are called isotopes
Periodic table mass is the weighted ____ of all of the ____ of each element
average, isotopes
Mixtures ______ be separated, but solutions _____ be.
can, can not
# of protons - # of electrons =
charge of element
Groups:
columns
molecule:
combination of at least 2 atoms in a specific arrangement held together by chemical bonds - can be an element or compound
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
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
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
To change a gas to a liquid, we have to increase the pressure a lot while maintaining the temperature, and call this process _____
deposition
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
H2, N2, O2, F2, CL2, BR2, I2
diatomic molecules
isomer
different orientations atoms can take in molecules with exactly the same number and ratio of atoms
Electron cloud contains 3rd subatomic particle outside of nucleus:
electrons
In neutral atoms... # of protons = # of ____
electrons
Pure substances can be _____ or ______
elements, compounds
reactivity with water, flammability, decomposition products upon heating
examples of chemical properties
color, melting point, boiling point, density, electrical conductivity
examples of physical properties
Polyatomic:
many atoms together
P4, S8
polyatomic molecules
_____ charge = # of protons > # electrons
positive
Density =
mass / volume
# of neutrons + # of protons =
mass number
mixture:
matter consisting of 2 or more pure substances that retain their individual identities + can be separated by physical methods
Pure substance:
matter having an invariant chemical composition + distinct properties
For a solid to change to a liquid, we have to add heat + call the process _____
melting
Homogenous:
mixture in uniform (solution) example: apple juice
Heterogenous:
mixture not uniform (can be separated) example: salad dressing
Bohr Model :
model with nucleus orbited by electrons, which are different in energy levels
All matter is composed of _____
molecules
increase mass = ____ dense
more
reduce volume = _____ dense
more
Protons :
much larger and heavier than electrons, have a positive charge mass = 1.67262158x10^-27 kg
ions form ____ based on where they are on the table.
naturally
______ charge = # protons < # electrons
negative
Mass is ...
neither created nor destroyed
Atoms are composed of 2 regions: ____ + ___
nucleus, electron cloud
Allotrope:
one of 2 or more distinct forms of an element examples: oxygen O2 + ozone O3; diamond + graphite (forms of carbon)
Rutherford's Gold Foil experiment
proposed that atoms consist of a tiny, massive, positive nucleus surrounded by electrons
Atomic number indicates the # of ___ in an atom
protons
Nucleus contains 2 of 3 subatomic particles:
protons + neutrons
All atoms are composed of ______, _____, + ______
protons, neutrons, + electrons
Matter occurs in nature as a ______ or ______
pure substance, mixture
Periods:
rows in the periodic table; are separated by the way the electrons around an atom fill
Atom:
smallest unit of matter that retains the identity of the substance
Four states of matter:
solids, liquids, gases, plasmas
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
For a solid to change to a gas, we have to lower the pressure significantly + call the process ______
sublimation
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)
spatial or geometric isomer:
the attachments look very similar but vary by how much they are attached in space
Chemistry is...
the study of matter
homonuclear diatomic molecules:
H2, N2, O2, F2, Cl2, Br2, I2
Group 17:
Halogen group
Polyatomic molecules:
- contain more than 2 atoms - most molecules - may contain more than one element - examples: water H20, methane CH4
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
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
Diatomic:
2 atoms together
Mercury + Bromine =
2 naturally occurring liquids
All molecules are composed of _____
Atoms
Aristotle and Plato:
Believed nature of matter was made of 4 elements (earth, fire, air and water)
5th state of matter:
Bose-Einstein Condensate
Heteronuclear diatomic molecules:
CO, HCl
Group 16:
Chalcogen group
_____ in an experiment are all the factors that the experimenter attempts to keep the same
Constant
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
How did king henry die?
King Henry Died By Drinking Chocolate Milk
2 extra rows on periodic table:
Lanthanides + Actinides
____ _____ provides information about percentages of different isotopes of each element
Mass spectrometer
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.
Groups 13 + 14:
Metalloids
Thomson
Plum pudding model; atoms were made from a positively charged substance with negatively charged electrons scattered about
Group 15:
Pnictogen group
___ are forms of matter
Substances
Group 3-12:
Transition Metals
Mendeleev:
first to publish a periodic table
For a liquid to change to a solid, we have to reduce the temperature + call the process ______
freezing
Elements:
fundamental substances; can not be separated into simpler substances by chemical methods example: iron metal (Fe)
Mixtures can be _____ or ______
homogenous, heterogeneous
Density is....
how closely packed together a substance is
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
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