1-2 Essential Ideas Flashcards
What is an element?
A substance composed of a single type of atom, cannot be broken down further. (Copper,gold,iron)
What is a compound?
A pure substance that can be decomposed into 2 or more elements (water, table salt)
What is the Law of conservation of matter?
Matter can neither be created or destroyed
What are atoms?
The smallest particle of an element that can enter into a chemical combination.
What is a molecule?
2 or more atoms joined by chemical bonds
Extensive property
Property that depends on the amount of matter present (mass/volume)
Intensive property
Property that does NOT depend on amount of matter present (temperature)
Heterogeneous mixture
Mixtures with compositions that change from point to point (water & oil, milk & cereal, concrete mixing)
Homogeneous mixture
(solution)
Mixtures with uniform compositions and appear visually the same (coffee, milk, air)
What is a hypothesis
Tentative explanation of observations that act as a guide for gathering and checking info
What is a law?
Statement that summarizes a vast number of experimental observations and describes some aspect of the world
What is a theory ?
Well substantiated comprehensive testable explanations of parts of nature
What are the 3 domains of chemistry?
Macroscopic (large everyday realm), microscopic (super small), symbolic (special language of chemistry -symbols, formulas, equations ect.)
Gas
Has no definite volume or shape, expands to fill container
Liquid
Has definite volume, but indefinite shape
Solid
Fixed shape and volume
Plasma
Gaseous state containing a large number of electrically charged particles (neon sign, lightning, fluorescent lights)
Types of pure substances
Elements & compounds
Daltons atomic theory (5 postulates)
1-matter made of atoms, 2-element = one type of atom, 3-properties of one type of atom differ from others, 4-compounds= 2 or more elements combined, 5-atoms neither created/ destroyed in chemical change
Law of multiple proportions
When 2 elements react to form more than 1 compound the masses react to form a ratio of small whole numbers
Law of definite proportions
All samples of a pure compound contain the same elements in the same proportion by mass
Atomic mass unit (amu)
Average mass of atoms
1 amu = 1.6605x10^-24 g
Fundamental unit of charge
e=1.602x10^-19 C
Electron
Negatively charged sub-particle, w/ low mass located outside the nucleus. Relative mass 0
