Intro To Chem Flashcards
Matter
Anything that occupies space & has mass
Mass
The quantity of matter that a substance possesses
Constant
Can be measured by its inertia
Not related to force of gravity
Weight
Measure of force with which a body is attracted toward Earth by gravity
Varies
Inertia
Resistance of an object to change in its position or motion
Density
The mass per unit volume of a substance
D=m/V
Atom
Smallest particle of an element that retains properties of that element & can enter into a chemical reaction
Element
Consists of only one kind of atoms
Compound
Substance composed of 2/more atoms joined together in a definite grouping
Molecule
Smallest particle of a substance that retains physical & chemical properties of that substance
Law of decomposition
A compound is composed of 2/more elements chemically combined in a definite ratio by weight
Physical properties
Those we can observe with our senses
Colour, odor, density, taste
Chemical properties
Those observed in regard to whether or not a substance changes chemically
Iron rusts in moist air, nitrogen does not burn, sodium reacts with water, Ag doesn’t react with water
Physical change
Doesn’t alter the identity of the substance
A change that alters some aspects of properties of matter, but composition remains constant
Breaking glass, cutting wood, melting ice
Chemical change
Alters the identity of the substance
Changes in the composition & structure of a substance
Always accompanied by energy changes
Burning wood, metabolism of food, milk going sour, baking a cake
Exothermic reaction
Chemical reaction that results in giving off heat to its surrounding
Endothermic reaction
Chemical reaction that results in overall absorption of heat from its surroundings
Activation energy
The minimum energy needed to get reaction going by increasing the energy of the reactants so they can combine
Law of conservation of matter
Matter can neither be created nor destroyed, only changed from one form to another
Mass of reactants = mass of products
Energy
The capacity to do work
Work
Work is done whenever a force is applied over a distance
Potential energy
Stored energy due to overcoming forces in nature
Kinetic energy
Energy of motion
Law of conservation of energy
Energy can be neither created nor destroyed
If system lose energy, surrounding must gain the lost energy
Law of conservation of mass & energy
Mass & energy are interchangeable under special conditions
Conditions have been created in nuclear reactors & accelerators
Einstein - E=mc^2
Qualitative observations
Involves descriptions of the nature of the substance under investigation
Quantitative observations
Involves making measurements to describe the substances under observation
Heat energy
Form of energy that transfers among particles in a substance (or system) by means of the kinetic energy of those particles; under KE theory - heat is transferred by particles bouncing into each other
Calorie
Unit of heat; the amount of heat needed to raise the temperature of 1g of water 1 degree Celsius
1 calorie = 4.18 joules
Precision
How repeatable the results are
Indicates reliability/reproducibility of a measurement
Accuracy
How close you are to the true value
Indicates how close a measurement is to its known/accepted value
Significant figures
All certain digits in a measurement
Solid
Definite size & shape
Liquid
Definite volume but takes shape of container
Gas
Neither definite size or shape
Distinct Substance
Can be subdivided into the smallest particle that still has the properties of that substance
Compounds & Elements
Mixture
Vary in their composition & constituents retain their properties
Heterogenous or Homogenous
Charge
Stored energy, has capacity to do work
Enthalpy
The heat content of a chemical system
Model
Visual, verbal or mathematical means of explaining how data is related to phenomena
Uncertainty
The limitation of the measuring instrument & the skill of the person making the measurement
