General Chemistry Notes

University:
Eastern Kentucky University
Course:
CHE 111 | General Chemistry
Academic year:

2023
Views:

280

Pages:

3
Author:

Payton Perry

Chemistry Elements: pure substances that consist of one type of atom ❖ Each element has an atomic number that represents the number of protons in a single atom of an element The periodic table is ordered by ascending number. Elements are divided into metals, metalloids, and nonmetals. Properties of Metals Metals make up most elements. Examples of metals are tin, osmium, zinc, and mercury. Metals exhibit the following properties: ❖ High luster (shiny) ❖ Metallic appearance ❖ Good conductor of electricity and heat ❖ Malleable (flexible) Properties of Nonmetals The properties of nonmetals are almost exactly opposite to those of metals. Examples of nonmetals are oxygen, hydrogen, and carbon. Nonmetals exhibit the following properties: ❖ Dull appearance ❖ Not malleable ❖ Brittle ❖ Do not conduct heat and electricity well ❖ Not magnetic Properties of Metalloids A metalloid has properties of nonmetals and metals. There are very few metalloids on the periodic table. Some common metalloids are boron, silicon, and arsenic. Metalloids exhibit the following properties: ❖ Dull and/or shiny ❖ Can conduct heat and electricity however not as well as metals (semiconductors) ❖ Often ductile (able to be bent and reshaped) and malleable Compounds: molecules made of atoms from DIFFERENT elements ❖ A molecule is any atoms connected by chemical bonds Physical and Chemical Changes Physical Change: Changes in the state of matter of a substance. In a physical change, there is no new substance made. The size, shape, and color of the matter might change; however the makeup of the substance will not. An easy way to identify a physical change is by seeing whether or not the change is reversible. If the change can be reversed, then it is physical. Examples of physical changes include: ❖ Melting or freezing an ice cube ❖ Origami ❖ Crumpling a piece of foil ❖ Boiling water Chemical Change: Changes where one chemical substance is transformed into a different substance(s). During a chemical change, the atoms and molecules are rearranged to produce completely new substances that were not there before. Some indications of chemical changes are the production of gas (bubbles), odor, or the production of energy such as heat. Examples of chemical changes include: ❖ Wood burning ❖ Cooking an egg ❖ A banana rotting ❖ Iron rusting