Unit 2 Flashcards
Matter
Anything that has mass and occupies space. Compound, element, mixture
Two types of matter
Heterogeneous and homogeneous
Compound
Two or more elements with new properties unlike the properties of the original substance. Example table salt
Element
Only one kind of Atom. can no longer be decomposed by ordinary chemical means. example silver
Mixture
Material composed of two or more substances which retain its own physical properties. Hetero or Homo. Also called solution
Changes that matter undergoes-physical properties
No change in composition. example mass, length, volume. Mixtures separated using their physical properties.
Changes that matter undergoes-physical change
-No new kinds of matter are formed -phase changes example freezing, boiling
mixtures can be separated by physical separation
Changes that matter undergoes-chemical properties
Changes into something new. Does it burn? React with acids?
Changes that matter undergoes-chemical changes
Changes that produce new kinds of matter that show brand-new properties. Example combustion burning, composition and decomposition, gas is given off
Law of definite composition
A compound always contains elements in certain definite compositions by having the same percentage by mass of each element in the compound
Law of multiple proportions
There can exist 2 or more compounds with different proportions of the same elements
Atomic number
Equals number of protons
Mass number
Equals number of protons plus number of neutrons
Atomic mass
Mass of Atom in AMU’s or u
Determining number of neutrons
Mass number-atomic number
Isotopes
Same Atom, different mass, different number of Neutrons
Why do protons not repel?
Strong nuclear force which is the strongest in the universe
Avogadro’s number
6.02x10^23
Mole
Amount of the substance that contains 6.02×10^23rd of any kind of chemical unit
Sig fig rule 1: 1-9
If answer starts with a digit 1-9 AND has decimal anywhere in number, ALL figures are significant (including zeroes)
Sig fig rule 2: 0 then decimal
If an answer starts with a zero and decimal, look to the first digit 1-9. That digit and all that follow (including zeroes) are significant.
Sig fig rule 3: 1-9 no decimal
All digits are significant unless the answer ends in zeros. Then all digits are significant except the last zeros.
Sig fig with addition and subtraction
Data with least number of decimal points decides the number of decimal points in the answer.
Sig figs with multiplication or division
Answer contains the same number of sig figs as the datum with the least number of sig figs.
Molar mass
Mass in grams of one mole of naturally occurring atoms of an element. G/mol
Physical properties
Color, density, solubility, taste, melting point, hardness, smell, malleability
Chemical properties
Flammable, can neutralize base, combustible, reacts to form gas, reacts to form precipitate
Physical changes
Melting, evaporation, rain, water to steam, salt dissolving in water, pepper suspended in water, crushing medicine, metal pulled to a wire
Chemical changes
Wood rotting, milk sours, sugar to caramel, iron rusts, changes colors, alka seltzer in water.
