Chapters 1 & 2 Flashcards
Catch-Up before the actual learning (64 cards)
What is the central principle of modern chemistry?
Materials around us are composed of exceedingly small particles called atoms, and the precise arrangement of these atoms into molecules or more complicated structures accounts for the many different characteristics of materials
What does it mean to synthesize molecules?
Build large ones from small ones
What is an experiment?
An observation of natural phenomena carried out in a controlled manner so that the results can be duplicated and rational conclusions can be made.
What is a law?
A concise statement or mathematical equation about a fundamental relationship or regularity of nature. Example: Conversion of mass law - states the mass, or quantity or matter, remains constant during any chemical change
Hypothesis?
A tentative explanation of some regularity of nature.
What occurred during Rosenbergs experiment?
After seeing bacteria ceased to divide when an electric current from platinum wire electrodes passed through the culture, Rosenberg was eventually able to propose the hypothesis that certain platinum compounds were responsible.
What is a theory?
a tested explanation of basic natural phenomena. Example: Molecular theory of gases - the theory that all gases are composed of very small particles called molecules
Scientific method
The general process of advancing scientific knowledge through observation, the framing of laws, hypothesis or theories.
Balances measure mass
The quantity of matter in a material
What is the law of conversion mass?
The total mass remains constant during a chemical change (chemical reaction).
What is the weight of an object?
The force of gravity exerted on it
What are the two principal ways of classifying matter?
By it’s physical state (liquid, solid, gas) and by its chemical constitution (element, compound, mixture)
What are the differences between solids, liquids, gas?
Solids: have rigidity and maintain their shapes when subjected to outside forces.
Liquids and Gases: Are fluids that easily change their shapes. What distinguishes gas from liquid is that gas is easily compressible. While water is expansible.
What is vapour?
Gaseous state of any kind of matter that normally exists as a liquid or a solid.
What is a physical change?
A change in the form of matter but not in its chemical identity. Example:
Dissolving one material in another such as sodium chloride (table salt) in water. Distillation can be used to separate the components of the liquid.
What is a chemical change?
A change in which one or more kinds of matter are transformed into a new kind of matter or several new kinds of matter. Example: The creation of rust on iron
What is a physical property?
A characteristic that can be observed for a material without changing its chemical identity. Examples: (Physical state (solid, liquid gas), melting point colour.
What is a chemical property?
Characteristic of a material involving its chemical change. (production of rust)
Define substances
A kind of matter that cannot be separated into other kinds of matter by nay physical process. Example (water)
What is a element?
A substance that cannot be decomposed by any chemical reaction into a simpler substance.
What is a compound?
Substance composed of two or more elements chemically combined.
Joseph Louis Proust: The law of definite porportions?
A pure compound, whatever its source, always contains definite or constant proportions of the elements mass. Example (Sodium Chloride 1.0000g = .3934 grams of sodium and 0.6066 gram of chlorine.
What are mixtures?
A mixture is a material that can be separated by physical means into two or more substances. Unlike a purecompound, a mixture has a variable composition. Example: Sodium chloride dissolved into water is a mixture.
How are mixtures classified?
Heterogenous: Mixutre that consists of physically distinct parts, each with different properties (salt and sugr).
Homogenous mixture: Uniform in its properites throughout given samples. (soium chloride dissolved in water)