AP Chem Chapter 0
Chemistry is the study of the properties and behavior of matter, in which matter is the physical space consisting of elements.
These elements consist of atoms that have unique properties, and those properties help chemists define their specialized function.
The importance of chemistry is for health care, protection of the environment, and the supply of energy for society
To classify matter, there are three stages known as:
Gas: Has no fixed volume or shape, and can be compressed or expanded to a small or larger volume
Has high speeds and collides repeatedly with other molecules or its own container
Liquid: Distinct Volume based on the container, and can not be compressed
Packed closely together, and the rapid movement allows them to slide over one another, allowing liquid to pour
Solid: Has a definite shape and a define volume, not allowing it to be compressible.
Molecules barely move from their fixed positions.
Changes in temperature and pressure can cause a conversion from one state of matter to the other.
A pure substance is a chemical composition that does not change from sample to sample (table salt, water).
Elements are substances that can not be decomposed further
Compounds are substances composed of two or more elements
Mixtures are combinations of two or more substances (element or compound).
The law of definite proportions explains that a compound must always use the same elements no matter what.
Physical properties are properties that do not modify the identity or composition of a substance
Color, odor, hardness, density, melting point, boiling point
Chemical properties are substances that can change or react to form new substances
Intensive properties are used for properties that do not require an amount or substance
Extensive properties are ones that do.
Filtration is the physical process to separate solid pieces
Distillation is the physical process to separate liquids.
Work is energy transferred on an object, causing a displacement
Heat is energy transferred that causes the temperature to rise.
Using the formula W = F x d, where f, is the push or pull that is exerted onto an object.
Kinetic energy is an object that possesses the virtue of motion.
Potential energy is an object that stores energy when not in motion.
Gravitational forces like electrostatic potential energy arise from interactions between charged particles (eg. opposite charges attract, like charges repel)
Chemical energy is when bonds are formed, and becomes consumed when bonds break.
Quantitative measurements include numbers
Chemistry includes 7 base SI units, those are:
Meters for length; m
Kilograms for mass: kg
Kelvin for temperature: K
Seconds for Time: s or sec
Mole for the amount of substance: mol
Ampere for the electric current: A or amp
Candela for luminous intensity: cd
Prefixes for the base SI system
Sometimes, there will be derived SI units, where you have to use multiplication or division of two units to find the main unit.
Speed (distance/time) and Density (mass/volume) are derived SI units.
Exact numbers are defined values like conversion factors or counting
Inexact numbers mainly come from measurement tools that vary the amount.
Precision is how closely individuals agree with each other
Accuracy is how close individuals are to the true value.
Significant figures indicate how much precision there is based on the number of digits, with the last digit being uncertain.
Zeros between nonzero digits are always significant—1005 kg (four significant figures); 7.03 cm (three significant figures).
Zeros at the beginning of a number are never significant; they merely indicate the position of the decimal point—0.02 g (one significant figure); 0.0026 cm (two significant figures).
Zeros at the end of a number are significant if the number contains a decimal point—0.0200 g (three significant figures); 3.0 cm (two significant figures).
For calculating, the number with the least significant figures will always round to that amount in the final answer.