Midterm Exam Flashcards
Chemical Properties
flammability, toxicity, reactivity, combustion, acidity
Physical Properties
density, color, hardness, reflectivity
chemistry
the branch of science that deals with the properties, composition, and structure of elements and compounds
Scientific Method
- observe
- state the problem
- form a hypothesis
- test hypothesis
- draw a conclusion
- communicate results
hypothesis
testable prediction
theories
generalizations made from many experiments
laws
generalizations that allow us to predict how things in nature will behave
SI Units
length: meter
mass: kilogram
time: second
temperature: kelvin
amount of a substance: mole
electric current: ampere
luminous intensity: candela
Dalton’s atomic theory
- all matter is composed of extremely small particles called atoms (wrong)
- atoms of a given element are identical in size, mass, and other properties (wrong)
- atoms cannot be subdivided, created, or destroyed (wrong)
- atoms of different elements combine in simple whole number ratios
- in chemical reactions, atoms are combined, separated, or rearranged
law of conservation of mass
matter cannot be created nor destroyed by normal means
law of conservation of energy
energy cannot be created nor destroyed but may be converted from one form to another
law of definite proportions
compounds are made up of the same ratio of elements no matter how much there is or where they are found
law of multiple proportions
if two or more compounds are composed of the same elements, then the ratio of the masses of the second elements combined with a certain mass of the first will always be small, whole numbers
Thomsons’ Cathode Ray Tube Conclusions
- electricity is composed of particles of matter (electrons)
- electrons are negatively charged
- electrons are very small
Oil Drop Conclusions
- mass of an electron is 1/2000 of a hydrogen atom
- same charge, but negative
Rutherford’s Gold Foil Conclusions
- the atom is composed of mostly empty space
- there is a small but very dense central core (nucleus)
- the nucleus has a positive charge