Chp 1 Essential Ideas

1.1 Chemistry in Context

Chem is interconnected to all other parts of STEM

chemistry - the study of the composition, properties, and interactions of matter

Theories - well-substantiated, comprehensive, testable explanations of particular aspects of nature

            Ex: Darwin’s theory of evolution. well substantiated because it incorporates laws, hypotheses & facts in its explanation of the natural world. This theory is testable thanks to fossil records.

            mnemonic:

scientific method - question & observation →law/hypothesis →theory + experimental verification of hypothesis (whether or not it supports or refutes) → adjustments of the theory

Domains of Chemistry

chemists study: macroscopic, microscopic & symbolic domains

Macroscopic

  • large enough for humans to see, like when you see your ice melt

  • so observing/measuring physical & chemical properties like density, solubility & setting stuff on fire.

Microscopic

  • soooo tiny you gotta use your imagination. micro reality big imagination

  • ions, electrons, protons, neutrons, & chemical bonds + biological cells

Symbolic

  • it’s the middle ground between macro & micro. symbols in chem help you understand what happens at both of these levels.

    Q what are examples of symbolic domain?

    • Chemical symbols (such as those used in the periodic table), chemical formulas, and chemical equations are part of the symbolic domain, as are graphs, drawings, and calculations.

EXAMPLE of all of the domains combined via water.

so even though you can see the states of water, it can be represented with (s) (g) and (l), though at a microscopic level these symbols differentiate how the molecules are spaced

1.2 Phases & Classifications of Matter

matter - everything that occupies space & has mass

  • solid - rigid shape, definite shape, fairly consistent volume

  • liquid - defitine volume but indefinite shape

  • gas - neither defitine volume nor shape

plasma - gaseous state of matter that contains appreciable numbers of electrically charged particles

mass - fundamental property indicating amount of matter

weight -force that gravity exerts on an object

law of conservation of matter - when matter converts/changes forms there is no change in the total amount of matter present

pure substance - can be decomposed into two or more elements

elements - substance that is made out of a SINGLE TYPE OF ATOM. cannot be decomposed by chemical change

compounds - pire substance that can be decomposed into two or more elements

mixture - matter that can be separated into its components by physical means

  • heterogeneous mixture - combination of subtsances; composition varies from point to point

  • homogeneous mixture (solution) - combintion of substances. uniform composition

atom - smallest particle of an element that can enter into a chemical combination

molecule - bonded two or more atoms of the same or diff elements

1.3 Physical & Chemical Properties

physical property - characteristic @ matter not associated w any change in its chemical composition

→physical change

chemical property - behavior that is related to the change of one kind of matter into another kind of matter

→chemical change - change producing a diff kind of matter than the og

extensive property - property of substance that depends on the amount of substance present

intensive property - property of substance that DOES NOT depend on the amount of substance present

1.4 Measurements

units - standard of comparsion for measurements

International System/ SI units

Derived SI units

calculation of density - density = mass/volume

1.5 Measurement Uncertainty, Accuracy & Precision

exact number - # derived by counting or by defition

every measurement has some uncertainty

Significant Figures

captive zeros -

leading zeros -

  1. addition/subtraction - round to the same # of decimal places as the # with the least amount of deicmal places

  2. multication/division - round the result to the same # of digits as the # with the least sig figs

  3. look @ the rounding rule…

Accuracy & Precision

precise - if they yield similar results when repeated a bunch of times

accuracy - accurate results agree with a true value

1.6 Mathematical Treatment of Measurement Results

speed = distance/time

dimesonal analysis is based on the units of quantities must be subjected to the same mathematical operations as their associated numbers

unit conversions

temperature units

Celsius scale - 0 freezing water 100 boiling

fahrenheit scale - freezing point of water is 32 degrees F & boiling 212. space between divided into 180 parts aka degrees

LEARN THE TEMP conversions for celisus & F

TK=T°C+273.15TK=T°C+273.15

T°C=TK−273.15