Chemistry - Ch 1 Flashcards
Matter
Physical material of the universe; anything that has mass and occupies space
Chemistry
Study of materials and the changes that materials undergo
Property
Characteristic that allows us to recognize a particular type of matter and to distinguish it from other types
Elements
Basic substances; about 100 in world
Atoms
Infinitesimally small building blocks of matter
Molecules
Combo of 2+ atoms joined in specific shapes
States of matter
Gas, liquid, solid
Gas
Vapor; no fixed volume or shape; conforms to volume & shape of its container
Liquid
Distinct volume, no specific shape; assumes shape of container
Solid
Definite shape & volume
Pure substance (substance)
Matter with distinct properties & a composition that does not vary from sample to sample
Compounds
Substances composed of 2+ elements; contain 2+ kinds of atoms
Mixtures
Combos of 2+ substances in which each substance retains its own chemical identity
Law of constant composition (law of definite proportions)
Observation that the elemental composition of a pure compound is always the same; put forth by Louis Proust, ~1800
Solutions
Homogeneous mixtures
Physical properties
Observed w/o changing the identity & composition of the substance
Chemical properties
Describe the way a substance may change (react) to form other substances
Intensive properties
Properties like temperature, melting point, density; do not depend on the amount of the sample being examined; can be used to ID substances
Extensive properties
Depend on quantity of sample (ex. Mass, volume)
Physical change
Substance changes physical appearance but not composition (same substance b4 & after)
Chemical change/reaction
Substance is transformed into a chemically different substance (hydrogen burning, changing to water; penny giving off a gas in nitric acid)
Filtration
Separating a mixture into component parts
Distillation
Part of separating components of a homogeneous mixture; depends on different abilities of substances to form gases (evaporating water from salt water leaving only salt)
Chromatography
“Writing of colors”; abilities of substances to adhere to surfaces of various solids (paper, starch); can be used to separate mixtures
Metric system
Units used for scientific measurements
SI units
Systeme International d’Unites; 7 base units from which all other units are derived (kg, meter, second, Kelvin, mole - amt of substance; ampere - electric current; candela (cd) - luminous intensity)
Giga (G)
10^9
Mega (M)
10^6
Kilo (k)
10^3
Deci (d)
10^-1
Centi (c)
10^-2
Milli (m)
10^-3
Micro (mu)
10^-6
Nano (n)
10^-9
Pico (p)
10^-12
Femto (f)
10^ -15
Mass
Measure of the amount of material in an object
Temperature
Measure of hotness or coldness of an object
Celsius
Everyday scale in most countries; based on 0 freezing, 100 boiling; C = 5/9 (F-32)
Fahrenheit
Temp scale in US; F= 9/5 (C) + 32
Kelvin
K= C + 273.15
Density
Amount of mass in a unit volume of a substance; = mass/volume
Exact numbers
Those whose values are known exactly
Inexact numbers
Those whose value a have some uncertainty
Precision
How closely individual measurements agree with one another
Accuracy
How closely individual measurements agree with the correct/true value
Significant figures
All digits of a measured quantity, including the uncertain one; zeroes btwn non zeroes always significant; zeroes @ beginning never significant; zeroes @ end significant if # has a decimal
Dimensional analysis
Aid in problem solving
Scientific method
Dynamic process to answer questions about our physical world; observations/experiments lead to scientific laws; observations also lead to tentative explanations (hypotheses); hypothesis tested/refined –> theory may develop
Scientific laws
General rules that summarize how nature behaves
