Chemistry Ch 1&2: Matter and Measurements

Extensive Property
depends on the amount of matter present
(ex: volume, mass)
Intensive Property
depends on the identity of the substance (ex: boiling point, density, conductivity)
Physical Property
can be observed without changing the identity of the substance (ex: melting point, density, magnetic)
Chemical Property
describes the ability of a substance to undergo changes in identity (ex: flammable, tarnishes in air)
Physical Change
changes the form but not the properties or identity of a substance (ex: sugar cube dissolving in water, ice melting, grinding spices)
Chemical Change
changes the identity and properties of a substance (ex: rusting iron, burning a log)
Element
Composed of identical atoms
Matter that cannot be seperated (pure substance) or be chemically decomposed
(ex: copper wire, aluminum foil, graphite)
Compound
composed of 2 or more elements in a fixed ratio
properties differ from those of individual elements
Matter that can’t be physically seperated (pure substance) but can be chemically decomposed
(ex: table salt, sugar)
Law of Definite Compostition
a given compound always contains the same, fixed ratio of elements
Law of Multiple Proportions
Elements can combine in different ratios to form different compounds
Mixture
matter that can be physically seperated
Solution
Homongeneous Mixture(matter that can be physically seperated and has a uniform composition)
very small particles
no Tyndall effect
particles don’t settle
(ex: rubbing alcohol, salt water)
Colloid
Heterogeneous mixture (matter that can be physically seperated and has a non-uniform composition)
medium-sized particles
Tyndall effect
particles don’t settle
(ex: milk, mayonnaise, fog)
Suspension
heterogenous mixture(matter that can be physically seperated and has a non-uniform composition)
Tyndall effect
particles settle
(ex: fresh squeezed lemonade, muddy water, italian salad dressing)
Prefix Memory Help
Miss-Mega (M)
Kathy- Kilo (k)
Hall- Hepta (h)
Drank- Deka (da)
Gatorade- Gram (g)
Milk- Meter (m)
(and)
Lemonade- Liter (L)
During- Deci (d)
Class- Centi (c)
Monday- Milli (m)
Morning- Micro (u)
(and)
Never-Nano (n)
Peed- Pico (p)
Scientific Method
1. Ask a question
2. Observe and collect date
3. Make a hypothesis
4. Test your hypothesis (experiment)
5. Draw conclusions
Scientific Law
a general statement based on the observed behavior of matter to which no exception is known
Theory
a broad generalization that explains a body of facts or phenomena (can be changed later/ part of a law if proved correct enough)
Quantitative Data
Numerical data such as mass or density
Qualitative
descriptive non-numerical data such as color or shape
Precision
the closeness of a set of measures of the same quantities made in the same way (repitition)
Accuracy
determined by the agreement between the measured quantity and the correct value (as close to the target as possible)
Percent Error
accepted value- experimental value/ accepted value * 100
Rules for counting significant figures
1. Leading zeros do NOT count
2. Captive zeros ALWAYS count
3. Trailing zeros ONLY count IF there is a decimal at the end
50 (1)
50.(2)
50.00 (4)
.00005 (1)
0.05 (1)
0.50 (2)
Rules for Adding, Subtracting, Multiplying, and Dividing Significant Figures
1. the answer should have the same number of decimal places as the measurement with the least number of decimal places (the least accurate measurement)
Celsius to Kelvin Temperature Conversion formula
C+273= K
Density
Mass divided by Volume
solids: grams/cm^3
liquids: grams/mL
gases: grams/L
x

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