Chem Unit 2 2
Terms
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- Matter
- Anything that has mass and occupies space
- Mass
- quantity of matter in an object
- Weight
- force produced by gravity acting on a mass
- 3 States of Matter
- Solid, Liquid, Gas
- 3 States of Matter depend on...
- the strength of intermolecular forces
- Laws of Conversation of Matter
- matter cannot be created nor detroyed, it simply changes form
- Physical Properties
-
characteristics of matter that can be measured without changing its chemical nature
Ex. size, color, odor - Physical Change
-
a change that affects only the physical properties
Ex. boiling, freezing - Chemical Properties
- characteristics of matter that can only be observed when substances interact with one another
- Chemical Change
- a change that produces one or more new substances
- Evidence of a Chemical Change (5)
-
1. evolution of a gas. (bubbles are seen)
2. formation of a precipitate
3. evolution or absorption of heat
4. emission of light
5. a color change as the reaction occurs - Atoms
- basic unit of matter
- Elements
-
the simplest substance from which more complex substances are made///
substance that cannot be broken down into other substances by chemical methods
(periodic table) - Molocules
- a neutral group of atoms held together by covalent bonds (charge=0)
- Compound
- substance made up of two or more elements chemically combined
- Allotrope
-
one of a number of different molecular or crystalline forms of an element
Ex. forms of carbon (graphite, diamond)
Ex. oxygen and ozone - Mixture
-
collection of 2 or more pure substances PHYSICALLY mixed together
Ex. sand and water
(can be separated by non -chemical methods, like evaporation and sifting) - Pure Substances
- all molocules are identical
- Homogeneous Mixture
-
mixture containing substances that are uniformly distributed
Ex. SOLUTIONS, alloys - Heterogeneous Mixture
-
mixture containing substances that are not uniformly distributed
Ex. granite - 2 Ways to Separate Mixtures
-
1. Distillation
2. Filteration - Distillation
-
separation of substances in a mixture based on their different boiling and cooling points
Ex. water and alcohol - Filteration
- separation of substances in a mixture based on the size of the particles
- Density
- the amount of matter present in a given volume of a substance
- Density Formula
-
mass/ volume
Ex. g/ mL or g/ cm3 - Specific Gravity
- the ratio of the density of a given liquid to the density of water
- Energy
- the capacity to do work
- Law of Conservation of Energy
- energy cannot be created or detroyed. it simply changes form
- 2 Types Energy
- kinetic energy + potential energy
- Kinetic Energy
- energy a moving object has becuase of its motion
- Potential Energy
- energy an object has because of its position (stored energy)
- Heat
- flow of energy due to a temperature difference
- Temperature
- measure of the average kinetic energy of the particles in a substance
- SI Unit for temperature
- Kelvin
- Absolute Zero
- the lowest temperature in the Kevlin scale (absence of motion)
- Exothermic
- heat is released during a reaction (warm)
- Endothermic
- absorption of energy in a reaction (cold)
- Calorie
- the amount of energy needed to raise one gram of water one degree Celcius
- SI Unit for Energy
- joule
- 1 cal= ___ Joule
- 4.184 Joule
- Specific Heat
- the amount of energy required to raise one gram of substance one degree Kelvin
- Calculating Specific Heat
-
Q= s*m*T
energy required= specific heat capacity*mass* change in temperature
J=(J/g C) (g) (change temp C) - Kevlin to Celcius
- C= K-273
- Celcius to Kelvin
- K= C+273