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83 Cards in this Set
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scientific method |
process by which a set of observations leads to a model of reality |
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1.State the reason for the study 2. Observation - process of watching and collecting data, form a law (measurements involving nature) 3. Hypothesis - analysis of data, educated guess 4. Experiment - controlled observation specifically designed to test a hypothesis 5. Theory - one or more confirmed hypotheses, predicts behavior beyond the observations and laws it was formed from |
Step of the Scientific Method |
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scientific theory |
a broad, working hypotheses based upon extensive experimental evidence, has undergone rigorous testing and will have great predictive power |
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hypothesis |
analysis of data, educated guess |
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scientific law |
statement based on recognizing patterns in repeated experimental observations, which can be used to summarize observations or formulate a mathematical relationship between them, but does not explain the cause |
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chemistry |
a world we cannot see, plays an integral role in all that goes on around us; a physical science* that explores and describes our world microscopically in both qualitative and quantitative detail; describes changes in matter |
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physical science |
analyze the nature and properties of energy and non-living matter |
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chemical science |
provides molecular reasons for out macroscopic observations |
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1. Understanding how chemistry works develops critical thinking 2. It affects the individual, social, political, and economic choices we make 3. It helps us make better informed choices that benefit our lives |
Why is chemical science important? |
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chemical reaction |
involve a manipulation or change in the basic unit of matter |
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elements |
basic units of matter, can not be broken down further, have names and are represented by symbols, made up of atoms |
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atoms |
smallest identifiable unit of an element, made up of sub-atomic particles |
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compound |
a substance composed of two or more elements in fixed proportions (Ex: water, table salt, sugar) |
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molecule |
two or more atoms bonded together |
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molecule --> atom --> element --> compound |
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matter |
the physical material of the universe (gases, liquids, and solids) |
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mass |
the amount of matter |
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weight (w) = mass (m) x acceleration due to gravitational pull (g)w = mg Matter occupies a 3-D volume (v) of space. |
How is mass different than weight? |
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Lavoisier |
combustion in air was studied by many scientists, the early though was that when something burned, a substance (phlogiston) was released, he tested this idea by controlled investigations, these experiments involved meticulous measurements of mass before and after a combustion reaction, found that air was required in the combustion process and the mass before and after was the same (phlogiston not released), led to the Law of Conservation of Mass |
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Law of Conservation of Mass |
matter changes form during a chemical reaction, but cannot be created or destroyed |
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Proust |
he proposed that different atoms combine to form compounds always in the same mass proportion |
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Law of Definite Proportions |
a compound always contain exactly the same proportion of elements, measured by mass |
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constant composition |
all samples of a given compound have the same proportions of elements that they are made up of |
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if the volume of a gas is decreased at a constant temperature, then its pressure will increase; reason is because the same amount of molecules are now in a smaller space which creates more collisions; V = a/P or PV = a or P1V1 = P2V2; P1 V1 are initial pressure and P2 V2 are final pressure; a is a constant of proportionality |
Boyle's Gas Law |
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pure substance |
either an element or a compound |
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mixture |
combination of two or more pure substances in variable proportions; the substance in a mixture may be either elements or compounds; classified by how uniformly the substances that compose them mix |
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heterogenous mixture |
mixture that separates into two or more regions with different compositions (Ex: oil and water) |
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homogenous mixute |
mixture that is uniform throughout the molecular level, has the same composition throughout; also called solutions (Ex: salt water) |
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1. Solid 2. Liquid 3. Gas 4. Plasma Gas |
Four States of Matter |
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Solid |
atoms or molecules are in close contact and in fixed locations; rigid, has a fixed or definite shape, incompressible |
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Liquid |
have a fixed volume and are incompressible, but don’t have an indefinite shape and take the shape of the container they are in |
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Gas |
atoms or molecules are not in close contact but are separated by large distances, molecules are in constant motion and often collide with one another, does not have a fixed shape or volume, compressible |
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Plasma Gas |
at very high temperatures this can be created, form of matter where electrons have been removed from atoms; good conductor of electricity and affected by magnetic fields |
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1. Crystalline - ordered structure 2. Amorphous - unordered structure |
Two Types of Solids |
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slower |
Colder molecules move ______, molecules lock together & expand. |
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melting |
solid to a liquid |
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freezing |
liquid to a solid |
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vaporization |
liquid to a gas |
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condensation |
gas to a liquid |
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sublimation |
solid to a gas |
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depostition |
gas to a solid |
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properties |
characteristics that distinguish a substance and make it unique |
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physical properties |
properties that a substance displays without changing its composition |
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chemical properties |
properties that a substance displays only when changing its composition |
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physical change |
matter changes appearance but not its composition |
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chemical change |
matter changes its composition |
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chemical formula |
the written formula (elements with subscripts) for a compound |
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structural formula |
picture formula of the shape of a compound |
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Law of Multiple Proportions |
same pair of elements can combine in different proportions to form compounds having very different properties |
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nucleus |
dense, positively charged core of an atom, surrounded by negatively charged electrons |
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electrons (e-) |
smallest particle with a negative charge, found outside the nucleus |
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neutrons (n0) |
large particle that is neutral charged or has no charge, found in the nucleus |
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protons (p+) |
large particle that has a positive charge, found in the nucleus |
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qualitative information |
observation or description based info |
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quantitative information |
measurement based, numbers info |
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states that if the temperature of a sample of gas is increased at constant pressure, it's volume will increase in direct proportion; V = bT or V1/T1 = V2/T2; b is a constant of proportionality, T is temperature in Kelvins |
Charles's Gas Law |
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combines Charles's and Boyle's laws; used in cases where more than one property of gases changes at a time; P1V1/T1 = P2V2/T2 |
Combined Gas Law |
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1. Rutherford 2. Bohr |
Models of Atom Structure |
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described the atom as a tiny, dense, positively charged core called a nucleus surrounded by lighter, negatively charged electrons. Another way of thinking about this model was that the atom was seen to be like a mini solar system where the electrons orbit the nucleus like planets orbiting around the sun |
Rutherford's Model of the Atom |
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saw that Rutherford's model was flawed, proposed that the electrons could only orbit the nucleus in certain special orbits at different energy levels around the nucleus, looks like a target |
Bohr's Model of the Atom |
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precision |
how well a device can reproduce a measurement |
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accurate |
how close a measurement can be to the correct answer |
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protons and neutrons make up the nucleus, surrounded by electrons |
Structure of an atom |
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density = mass/volume |
density |
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pressure |
force applied over a unit of area |
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temperature |
a physical property of matter, average energy of particles of matter in motion (kinetic energy), measures how hot or cold a substance is in relation to another substance, three forms of measurement: Fahrenheit, Celsius, Kelvin |
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Fahrenheit |
unit named for the German physicist, common in US, freezing at 32 degrees |
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Celsius |
named for a Swedish astronomer, common across the world, freezing at 0 degrees |
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Kelvin |
unit named for the British mathematician and physicist, SI unit of temperature, freezing at 0 degrees |
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heat |
flow of energy due to differences in temperature, measures total energy |
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energy |
the capacity to do work; (kg*m2)/sec |
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91 |
There are ______ naturally occurring elements |
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symbol |
Letter(s) representing an elements |
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Atomic number Z |
number of protons, lower number |
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Mass number A |
number of neutrons and protons |
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A - Z = n0 |
Atomic number _____ - atomic number _____ = number of neutrons |
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neutral atom |
equal number of protons and electrons in an atom |
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ions |
electrons can be removed or added to neutral atoms to create |
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cat ion |
positively charged ion, looses electrons |
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an ion |
negatively charged ion, gains electrons |
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isotope |
elements where there may be added or missing neutrons, most elements have more than one, lightest is the most stable and heaviest least stable |
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model suggesting that the entire atom was positively charged with negative electrons spread throughout |
Plum Pudding Model |
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transition metals |
elements most likely to form variable charges |
