Ch. 1 Flashcards
Qualitative
Consisting of general observations about the system
Quantitative
Numbers obtained by various measurements of the system
Hypothesis
A tentative explanation for a set of observations
Law in science
Concise verbal or mathematical statement of a relationship between phenomena that is always the same under the same conditions
Theory
A unifying principle that explains a Body of facts and/or those laws that are based on them
Matter
Anything that occupies space and has mass
See: ice cubes, books, pen
Cant see- air, oxygen, germs
Substance
A form of matter that has a definite composition and distinct properties
Examples: Water, ammonia, sucrose (table sugar), gold
Mixture
A combination of two or more substances in which the substances retain their distinct identities
Examples: air, soft drinks, milk and cement
Homogeneous mixture
The composition of the mixture is the same throughout
Ex: Sugar in water, rain, vodka, steel, air
Heterogeneous mixture
Composition is not uniform
Iron fillings mixed with sand grains, cereal, ice in soda, blood
Element
A substance that cannot be separated into simpler substances by chemical means (there are 118 identified so far)
Examples: Calcium, chlorine, copper, bromine…
Compound
A substance composed of atoms of two or more elements chemically united in fixed proportions (water)
Two types of matter
Mixtures and substances
Two types of mixtures
Homogeneous and heterogeneous
Two types of substances
Compounds and elements
Three states of matter
Solid, liquid and gas
Physical property of matter
Can be measured and observed without changing the composition or identity of a substance
physical change: frost forms, silver fork tarnishes
Chemical property of matter
To observe a property you have to carry out a chemical change
Chemical changes: cornstalk grows after seed is watered
Mass
Quantity of matter in a given sample of a substance
Volume
Defined as length cubed
Density
Mass of an object divided by its volume
Intensive property (doesn’t matter how much matter is being considered)
Equation for Density
Mass divided by volume
Precision
How closely two or more measurements of the same quantity agree with one another
Accuracy
How close a measurement is to the true value of the quantity that was measured