Matter and Change
Section 1: Chemistry is a Physical Science
Chemistry: the study of composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these processes
Chemical: any substance that has a definite composition
Six Branches of Chemistry: Organic, Inorganic, Physical, Analytical, Biochemistry, Theoretical chemistry
- Organic Chemistry: study of carbon-containing compounds
- Inorganic Chemistry: study of non-organic substances, many of which have organic fragments bonded to metals(organometallics)
- Physical Chemistry: the study of the properties and changes of matter and their relation to energy
- Analytical Chemistry: the identification of the components and composition of materials
- Biochemistry: the study of substances and processes occurring in living things
- Theoretical chemistry: the use of mathematics and computers to understand the principles behind observed chemical behavior and to design and predict the properties of new compounds
Two types of research: Basic and Applied
- Basic-purely just for expanding knowledge
- Applied-carried out to solve a problem
Section 2: Matter and its Properties
Atoms: smallest unit of an element that maintains the chemical identity of that element
Element: a pure substance that cannot be broken down into simpler, stable substances and is made of one type of atoms
Compound: a substance that can be broken down into simple stable substances. Made from atoms of two or more elements that are chemically bonded
2 types of Properties: Extensive and Intensive
- Extensive: depends on the amount of matter that is there(ex. volume, mass, energy)
- Intensive: doens't depend on the amount of matter that is there(ex. density, melting point, conductability)
Physical Properties and Physical Changes
- Physical Properties: a characteristic that can be observed or measured without changing the identity of the substance
- Physical Change: a change in the substance that doesn't involve a change in the identity of the substance(ex. melting, boiling, sublimation)
States of matter
- Solid: the matter has a definite volume and shape
- Liquid: the matter has a definite volume but no definite shape
- Gas: the matter has no definite volume nor definite shape
- Plasma: a high-temperature physical state of matter in which atoms atoms lose most of their electrons
Chemical Properties and Changes
- Chemical Property: a substance's ability to undergo changes that transform in into different substances
- Chemical Change/Chemical Reaction: when one or more substances are converted into different substances
A mixture is a blend of two or more kinds of matter, each retains its own identity and properties. There are two types of mixtures: Homogenous and Heterogenous. Some mixtures are uniform in composition which are homogeneous mixtures . They have the same proportion of components throughout. Homogeneous mixtures are also called solutions. Other mixtures are not uniform throughout which are heterogeneous mixtures . For example, in a mixture of clay and water, heavier clay particles concentrate near the bottom of the container.
A pure substance is homogenous as a single entity. A pure substance has a fixed composition. Every sample of a given pure substance has exactly the same characteristic properties. Every sample of a given pure substance has exactly the same composition.