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42 terms

Chemistry #1

chemistry #1
STUDY
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matter
anything that has mass and occupies space
chemistry
study of characteristics, composition and transformation of matter
mass
is the amount of matter
weight
is the amount of gravitational pull on an object
solid - physical states
shape = definite
volume = definite
compressible = no
organization = very ordered
liquid - physical states
shape = indefinite
volume = definite
compressible = very little
organization = ordered (somewhat)
Gas - physical states
shape = indefinite
volume = no definite
compressible = highly
organization = very little order
state of matter
depends on its temperature, pressure and the strength of the intermolecular forces involved.
plasma
1. is the fourth physical state of matter
2. consists of a collection of free-moving electrons and ions - atoms that have lost electrons
properties (definition & 2 types)
1. are the distinguishing characteristics of a substance that are used to in its identification and description.
2. each substance is unique
3. Chemical and physical
Physical properties
1. of matter are those that we can observe or measure. 2. The chemical composition is not changed.
3. The physical appearance may change.
Ex. visibility, mass, chemical structure, color, smell, boiling point, melting point, density
Chemical properties
1. of matter are those that relate to how the substance changes in composition ,how it interacts with other substances, or resists change to form a new substance.
2. Interactions between substances are greatly influenced by temperature and pressure.
Ex. corrosive, combustion, reaction w/O2, reaction or no reaction
Changes in matter - physical
is process in which a substance changes its physical form or appearance but not its basic composition (chemical composition). A new substance is never formed as a result of physical change.
Changes in matter - chemical
1. is a process in which a substance changes in the chemical composition .
2. Matter is transformed completely into different materials and new substances (at least one) are formed.
3. A chemical reaction happens, the new substance(s) has different composition and chemical properties.
pure substance
1. is a single kind of matter that cannot be separated into other kinds of matter by any physical means (require chemical means).
2. It always has a DEFINITE and
CONSTANT COMPOSITION.
3. Either element or compound
Ex. one substance present, two phases present (ice water)
Mixtures
1. is a combination of two or more substances in which each substance retains its chemical identity.
2. They are PHYSICALLY mixed rather than chemically combined.
3. Variable composition
Example: rock salt and sand. The components of a mixture can be separated by physical means.
hetrogeneous mixture
1. are mixtures that do not have uniform composition
and appearance throughout.
2. It contains visibly different phases (parts), each of
which has different properties.

Example: sulfur and iron, rocks, soils and wood
homogeneous mixture
1. are mixtures that contains only ONE visibly distinct PHASE, which has uniform properties throughout.

Example: sugar-water ( all the sugar has dissolved)
element
1. is a pure substance that cannot be broken down into simpler pure substances by ordinary chemical means such as a reaction, an electric current, heat, or a beam of light. Cannot be broken down by physical means.
2. Made of atoms.
3. A sample of an element is composed of atoms of a single type
4. definite composition
Ex. Copper, Sulfur
H, C, P, N
element ----> atom
compound
1. is a pure substance that can be broken down into two or more simpler pure substances by CHEMICAL means.
2. The products are elements or simpler compounds.
3. A compounds properties are always different from those of its component elements, b/c the elements are chemically rather than physically combined
4. made of molecules
5. definite composition
ex. Co2, H2O, NaCl
compound -----> molecule ------>atom
atom
1. smallest identifiable piece of an element which has the element's properties.
2. smallest particle of an element that can exist
3. is the LIMIT OF CHEMICAL SUBDIVISION
molecules
- cluster of atoms bound tightly together
1. smallest identifiable piece of a compound.
2. molecules are made by atoms combined on definite proportions regardless of the source.
3. a group of two or more atoms that function as a unit b/c the atoms are tightly bound together
4. is the LIMIT OF PHYSICAL SUBDIVISION
5. smallest particle of a compound capable of a stable independent existence.
chemical symbol
is a one or two letter designation for an element derived from the element's name
diatomic molecule
molecule that contains two atoms
triatomic molecule
molecule that contains three atoms
tetratomic molecule
molecule that contains four atoms
pentatomic molecule
molecule that contains five atoms
hexatomic molecule
molecule that contains six atoms
heptatomic molecule
molecule that contains seven atoms
octatomic molecule
molecule that contains eight atoms
nonatomic molecule
molecule that contains nine atoms
homoatomic molecule
a molecule in which all atoms present are of the same kind (element). MUST BE AN ELEMENT
hetroatomic molecule
a molecule in which two or more kinds of atoms are present. MUST BE A COMPOUND
chemical formula
a notation made up of the chemical symbols of the elements present in a compound and numerical subscripts that indicate the number of atoms of each element present in a molecule of the compound
two phases
shows that it is not uniformly mixed
one phase
indicates that the mixture of two substances has uniform properties throughout
homogeneous
phase
a physically distinctive form of matter, such as a solid, liquid, gas or plasma
universe elements
hydrogen 91%
helium 9%
earth's elements
oxygen 60.1%
silicon 20.1%
human body element
H =60.5%
O = 25.7%
C =10.7%
N = 2.4%
sublimation
The transition of a substance from the solid phase
directly to the vapor phase, or vice versa, without passing through an intermediate liquid phase
evaporate
The conversion of a liquid (water) into a vapor (a
gaseous state) usually through the application of heat energy during the hydrologic cycle; the opposite of condensation.