Chapter 1 Flashcards
Observation
- first step in scientific method
- observe, describe, and measure some event in nature
- based in measurements called data
example:
A silver tray turns a dull gray color when left uncovered
Hypothesis
- possible interpretation of observations
- must be stated in a way that is tested by experiments
example:
Ice cubes has a greater volume than the liquid from which they were formed because the water molecules are farther apart in the ice structure than in the liquid structure.
Law
- summary of related observations
- statement that generalizes a body of observations or facts but does not provide an explanation why things happen the way they are
example:
The volume of a gas is directly proportional to its pressure.
Energy may be converted from one form to another, but the total quantity of energy remains constant.
Theory
- explanation of observations/ provides underlying reasons for observations
- well-tested, unifying principle explaining body of facts and laws based on them
example:
A gas is composed of small particles in constant motion.
Rules for Writing in Scientific Notation
- moving left = positive exponent example: 93,000,000 = 9.3 × 10^7 - moving right = negative exponent example: .00005114 = 5.114 × 10^−5
Metric System
- > length: meter (m)
- > volume: liter (L)
- > mass: gram (g)
- > temperature: degree Celsius (°C)
- > time: second
System International (SI) Units
- > length: meter (m)
- > volume: cubic meter (m^3)
- > mass: kilogram (kg)
- > temperature: kelvin (K)
- > time: second (s)
Metric Conversion Chart
Tm (10^12) -> Gm (10^9) -> Mm (10^6) -> km (10^3) -> m(base unit) -> dm (10^-1) -> cm (10^-2) -> mm (10^-3) -> μm (10^-6) -> nm (10^-9) -> pm (10^-12)
Important Conversions/ Formulas
1ml = 1cm^3 D = m ÷ v °F = 1.8(°C) + 32 °C = (°F -32) ÷ 1.8 K = °C +273 °C = K - 273
Mass
- measure of the quantity of material it contains
-measure of the quantity of matter - independent of acceleration of gravity
-measured on balance “kg”
measured by comparison to a known mass which does not depend on gravitational pull
Weight
- has meaning only when an object having a specific mass is placed in an acceleration field like gravitational field of the earth
- depends upon acceleration of gravity
- W = mg “Newton”
- measured on scale
measured by the movement it causes in a spring which depends on the gravitational pull
Density
- mass per unit volume (D = m ÷ v)
- larger mass substance relative to volume, denser and heavier the object
- varies according to change in temperature
- physical property of matter
- Describes how its particles are packed together (tighter particles, higher density)
- In general, temperature increases, motion particles increase, volume expansion (since mass constant at all temperatures, density decreases at increasing temperature)
- most substances become denser when colder BUT when water reaches its max density at 4°C, expands and becomes less dense
- Temperature increases, volume expands and becomes larger, causing decrease density
- Temperature drops, volume contracts and becomes smaller, increase density
States of Matter
- classified by physical states: solid, liquid, gas
- solid: definite shape, definite volume
- liquid: definite volume, no definite shape
- gas: no definite shape and volume; highly compressible
Physical Properties
- observable and measured characteristics without changing composition of substance
examples:
color, state of matter, melting point, boiling point, density, solubility, electric conductivity, heat conductivity, malleability, ductility, viscosity, hardness, odor, taste
Chemical Properties
- observable and measured characteristics where one or more substances/ reactants are transformed into one or more different substances/products
- molecular identity no longer remains the same
examples:
flammability, acidity, volatility, corrosiveness, electronegativity
