Question | Answer |
matter | anything that occupies space and has mass |
mass | measure of quantity of matter |
energy | capacity o move an object or transfer heat |
pure substance | matter that has the same chemical composition no matter what its origin ( cannot be separated into components by physical means) |
mixture | consist of tow or more pure substances and may vary in composition |
how many types of pure substances are there? what are they? | There are two. They are elements and compounds. |
element (pure substance) | substance that cannot be broken down into simpler substances by even chemical reaction |
What are the building blocks of all matter? What do chemists use to classify them? | Elements. The periodic table |
elements can be a.... | metal or nonmetal |
a metal | is lustrous and has good electrical conductivity |
a nonmental | is not lustrous and has poor electrical conductivity |
element symbol | a shorthand version of an elements longer name |
compounds | substance composed of two or more elements. A compound has properties different form those of its component elements. |
chemical formula | describes the composition of a compound |
mixture | a combination of two or more substances that can vary in composition. |
what are the two types of mixtures? | homogeneous and heterogeneous |
homogeneous mixture | has uniform composition throughout and is often a solution. however not all solutions are liquids. |
heterogeneous mixture | doesn't have uniform composition throughout. ( salt and pepper mixture) |
macroscopic scale | matter we can with our eyes |
atom | smallest unit of an element that has the chemical properties of that element. |
molecules | two or more atoms bound together in a discrete arrangement. |
physical state, what are the three states? | a form that matter can take: solid, liquid, and gas. (also aqueous solution) |
solid (s) | fixed shape that isn't related to shape of a container holding it. a solid cannot be compressed. (particles tightly packed) |
liquid (l) | has no fixed shape. it takes the shape of its container. particles aren't in arranged structure and can be compressed slightly |
gas (g) | shape of its container (it fills it), volume of its container, particles widely separated and move indecently of one another |
aqueous solution (aq) | substance is dissolved in water |
qualitative observation | based on quality of matter such as color, shape, texture, luster, physical state |
quantitative observation | based on a numerical value like mass volume density or temperature |
physical properties | characteristic we can observe or measure without changing the composition of a substance |
kilo | k 10^3 |
centi | c 10^-2 |
milli | m 10^-3 |
micro | 10^-6 |
nano | 10^-9 |
volume | amount of space a substance occupies. v= lwh |
density | ratio of mass to volume d=m/v |
temperature | measure of how hot or cold something is |
boiling point | temperature at which liquid turns to gas |
what is the boiling point for water in F, C and K. | 212, 100, 375.15 |
melting point | temperature at which solid turns to liquid |
absolute temperature scale. | no negative values, 0 is the absolute coldest (kelvins) |
physical change | process that changes only the physical properties of a substance, not its chemical composition. |
ex of physical change | liquid to gas by heat |
chemical change (chemical reaction) | process in which one or more substances are converted into one or more new substances. |
ex of chemical change | a rusted penny |
chemical property | characteristic of a substance defined by its composition and the chemical changes it can undergo |
an inert element | doesn't react to any other element or compound |
ex of inert element | helium |
energy | capacity to do work and transfer heat |
work | force acts over a distance |
kinetic energy | energy of motion |
potential energy | energy possessed by an object because of its position |
ex of potential energy | chemical energy |
electric energy | associated with the passage of electricity; generally through metals |
all forms of energy can be | converted to one another |
scientific method | approach to asking questions and seeking answers that employs a variety of tools, techniques, and strategies |
how do scientists differ from other professionals | 1) test ideas by experimentation
2) organize their findings in a particular (often mathematical) ways
3) try to explain why things happen |
scientific inquiry includes | observations, hypotheses, laws, and theories |
observation | come from a naturally occurring event or a deliberate experimentation (controlled conditions) |
hypotheses | tentative explanation of the properties or behavior of matter that accounts for a set of observations and can be tested. |
hypotheses often lead to | further experimentation |
laws | when behavior of matter is so consistent that it appears to have universal validity |
scientific law | the way nature operates under specified conditions |
law of conservation of mass | mass of products obtained from a chemical reaction equals the mass of the substances that react |
after new information was found the law of conservation of mass became | the law of conservation of mass and energy |
theories | explain why observations, hypotheses, or laws apply under many different circumstances |
hypotheses and laws explain... | how nature works |
accidental but fortunate breakthroughs | Alexander Fleming: penicullin 1928, Henri Becquerel : radioactivity |
who said, "in the fields of observation chance favors only th prepared mind" | louis pasteur |
combinatorial chemistry | series of related chemical compounds is systematically prepared and tested for effectiveness in disease treatment |
Green chemistry/ sustainability | develop chemical processes that prevent pollution and dredge the amount of natural resources used to manufacture various consumer research and industrial products. |
main goal of green chemistry | prevent waste |