Chem 211 DL1 Chapter 1

the scientific study of matter and its properties, the changes that matter undergoes, and the energy associated with those changes

chemistry

anything that has mass and volume

matter

the types and amounts of simpler substances that make it up

composition

the three physical forms of all matter

states of matter

• has a fixed shape that does not conform to the container

• not defined by rigidity or hardness

• its particles lie next to each other in a regular, three-dimensional array

solid

• has a varying shape that conforms to the container but only to the extent of its volume

• has an upper surface

• the particles lie close together but move randomly

liquid

• has a varying shape that conforms to the container shape

• does not have a surface

• their particles are largely distanced and move randomly

gas

a characteristic that gives each substance its unique identity

property

characteristics a substance shows by itself, without changing into or interacting with another substance

physical property

occurs when a substance alters its physical properties, not its composition

physical change

characteristics a substance shows as it changes into or interacts with another substance

chemical property

occurs when one or more substances are converted into one or more substances with different composition and properties

chemical change

the ability to do work

energy

the energy due to the position of the object relative to other objects

potential energy

the energy due to the motion of the object

kinetic energy

process of creative proposals and testing aimed at objective verifiable discoveries of the causes of natural events

scientific method

facts that our ideas must explain

observation

pieces of quantitative information

data

a summary, often in mathematical form, of a universal observation

natural law

a proposal made to explain an observation

hypothesis

a set of procedural steps that tests a hypothesis

experiment

quantities that can have more than one value

variable

measures the effect of one variable on another while keeping all other variables constant

controlled experiment

formed based on experiments that test hypotheses about observations and distinguishes scientific thinking form speculation

model/theory

the process burning a material in air

combustion

a unit composed of one or more of the base units of the Système International d'Unités, a revised form of the metric system

SI unit

defines the standard for one of the seven physical physical quantities in the International System of Units

base unit

combinations of the seven base units

derived unit

the SI base unit for length

meter (m)

the amount of space matter occupies

volume (V)

derived SI unit for volume

cubic meter (m³)

a non-SI unit used to measure volume (larger)

liter (L)

another non-SI unit to measure volume (smaller)

milliliter (mL)

• the quantity of matter an object contains

• it is constant because an object's quantity of matter cannot change

mass

the SI unit of mass; the only unit with a prefix

kilogram (kg)

a variable that depends on the local gravitational field acting on the object

weight

the SI base unit of time

seconds (s)

ratios used to express a quantity in different units

conversion factor

a calculation method in which arithmetic steps are accompanied by cancelling units that represent physical dimensions

dimensional analysis

the mass of a sample of a substance divided by its volume

density (d)

a measure of how hot or cold one object is relative to another

temperature (T)

the energy that flows from an object with a higher temperature to an object with a lower temperature

heat

a graduated tube containing a fluid that expands when heated

thermometer

the base unit of temperature

kelvin (K)

sets the water freezing point at 0°C and its boiling point at 100°C

Celsius scale

• uses the same size degree as the Celsius scale

• the distance between the freezing point and boiling point of water is still 100 degrees, but is 273.15 degrees higher because of a different zero point

• all temperatures are positive

Kelvin scale

dependent on the amount of substance present; mass and volume

extensive property

independent of the amount of substance; density and temperature

intensive property

a characteristic of every measurement that results from the inexactness of the measuring device and the need to estimate when taking a reading

uncertainty

digits obtained in a measurements

• the greater the number of these, the greater the certainty of the measurement

significant figures

the process of removing digits based on a series of rules to obtain an answer with the proper of significant figures (or decimal places)

round off

has no uncertainty associated with them; they do not limit the number of significant figures in a calculation

exact number

reproducibility how close the measurements in a series are to each other

precision

refers to how close each measurement is to the actual value

accuracy

produces values that are either all higher or all lower than the actual value

• is often caused by a faulty device or by a consistent mistake intaking a reading

systematic error

in the absence of systematic error, produces values that are higher and lower than the actual value

• it always occurs but depends on the measurer's skill and the instrument's precision

random error

comparing a measuring device to a known standard

calibration

• Observation

• Hypothesis

• Experiment

• Model

Scientific Approach

• one is constant because an object's quantity of matter cannot change

• one is variable because it depends on the local gravitational field acting on the object

mass vs. weight

• one is a measure of how hot or cold one object is to relative to another

• one is the energy that flows from an object with higher temperature to one with lower temperature

temperature vs. heat

• one is independent of the amount of substance

• one is dependent of the amount of substance

intensive vs. extensive properties

• one is how close each measurement is to the actual value

• one is how close the measurements in a series are to each other

accuracy vs. precision

• one produces values that are either all higher or all lower than the actual value; occurs only by mistakes or faults

• one produces value that are higher and lower than the actual value; this will always occur

systematic vs. random error

mass/volume

density=

K = °C + 273.15

°C to K

°C = K - 273.15

K to °C

°F = 9/5 x °C + 32

°C to °F

°C = (°F -32) 5/9

°F to °C