Chapter 1 Vocabulary Flashcards
Pure Substance
same chemical and physical properties throughout; cannot be separated into simpler substances by a physical process
Can be an element or a compound
What is a physical process?
a transformation of a sample of matter that does not alter the chemical identity
Element
a pure substance that cannot be separated into simpler substances by any chemical process
Compound
a pure substance composed of two or more elements bonded together in fixed proportions; can be broken down into individual elements by chemical reactions
Mixture
combination of two or more substances; can be homogenous or heterogeneous
homogenous mixture
components are distributed uniformly throughout the sample and have no visible boundaries or regions
heterogenous mixture
the components are not distributed uniformly and may have distinct regions of different composition
Atom
smallest particle of an element that retains the chemical characteristics of that element
Molecule
assembly of two or more atoms that are held together in a characteristic pattern by chemical bonds
Chemical formula
notation for representing elements and compounds; consists of symbols of elements and subscripts identifying the number of atoms of each element in one molecule
Chemical reaction
the transformation of one or more substances into different substances
Chemical equations
Use chemical formulas to express
the identities of substances involved
in a reaction; Use coefficients to indicate
quantities of substances involved in
a reaction.
Law of Constant Composition
All samples of a particular compound contain the same elements combined in the same proportions.
Example:
* Water (H2O)
* Consists of two units of hydrogen (H) combined with one unit of oxygen (O)
* Elements and proportions are represented by chemical formulas.
Ions
compounds consisting of positively or negatively charged particles
Can be Cations: positively charged ions
Ex: Calcium ion is Ca^2+
Can be Anions: negatively charged ions
Ex: Hydroxide ion is OH^-
Ways to represent bonding and shape for an arrangement of atoms
structural formulas, ball-and-stick model, and space-filling model
Properties of Matter
Intensive property and extensive property
Intensive property
A property that is independent of the amount of substance present
Examples – color, luster, melting and boiling points, hardness, and density
Extensive Property
A property that varies with the quantity of the substance present
Examples: volume, mass
Physical Property
A property of a substance that can be observed without changing it into another substance
Examples: luster, hardness, color, state, melting point, boiling point, density
Chemical Property
A property of a substance that can be observed only by reacting it to form another substance
Examples: flammability
Density
Ratio of the mass of an object/substance to the volume of the object/substance
Density = mass/volume
States of matter
Solids: Definite shape and volume
Liquids: Occupies definite volume, but flows to assume the shape of its container
Gases (vapors): Neither definite shape nor volume; expands to fill its container
When there is a transformation from one
state to another due to addition or removal
of heat, a state change occurs.
Hypothesis
A tentative and testable explanation for an observation or a series of observations
Scientific Theory
A general explanation of widely observed phenomena that has been extensively tested and validated
Scientific Method
- observe natural phenomena
- generate predictions to test hypothesis
- test the hypothesis
- analyze the results: could lead back to refining the experiment, modifying the hypothesis, or rejecting the hypothesis
- establish a theory(or model): could continue to test in light of the additional observation
Accuracy
agreement between a measured value and accepted value
Precision
agreement between repeated measurements
Name the temperature scales and the temperature conversions
Fahrenheit, Celsius, and Kelvin
K = C + 273.15
C = 5/9 (F - 32)
F = 9/5C + 32
