Properties Are Used to Identify Matter 6.1 Properties Are Used to Identify Matter VOCABULARY physical properties chemical properties mixtures pure substances elements atoms compounds Physical properties can be observed without changing the chemical structure of a substance. Chemical properties describe a possible chemical change. Matter is made of atoms. Atoms are the smallest particles of each element. Elements, compounds, and mixtures together constitute all matter. Mixtures are made from two or more substances that are not chemically combined. Elements combine to form compounds. Elements are identified by names and chemical symbols. Some elements are found as paired atoms.

6.2 Atomic Theory VOCABULARY subatomic particles nucleus protons neutrons atomic number mass number atomic mass electrons electron shells unpaired electrons paired electrons Atoms are made of component particles called subatomic particles: protons, neutrons, and electrons. Every atom of any one element will have the same number of protons. Positive protons and neutral neutrons are found in the nucleus, and negative electrons are arranged in shells or orbits around the nucleus. There are an equal number of protons and electrons in an atom. Ions form when the number of electrons changes. The number of electrons in the outer shell determines the properties of the element.

Classifying Elements with the Periodic Table 6.3 VOCABULARY chemical families Elements can be classified or grouped in many different ways using physical and chemical properties. The groups include metals, non-metals, and metalloids. Some groups of elements have characteristic sets of common physical and chemical properties, and are called chemical families. The Periodic Table organizes elements in the following way: Metals are found on the left side, non-metals on the right, and metalloids in between. Chemical families are arranged in vertical groups. The table can also display the chemical symbol, atomic number, atomic mass, ion charge, density, and other information about each element.

Elements, Atoms, and the Atomic Theory CHAPTER Elements, Atoms, and the Atomic Theory 6 Matter is made of atoms and every element has its own unique type of atom. Elements are identified by names and chemical symbols. Atoms have a structure that determines their properties. Every atom is composed of three types of subatomic particles: protons, neutrons, and electrons. The number of electrons in the outer shell of an element’s atoms determines the properties of the element.

Elements, Atoms, and the Atomic Theory CHAPTER Elements, Atoms, and the Atomic Theory 6 The Periodic Table organizes elements in different ways. Metals are found on the left, non-metals on the right, and metalloids in between. Chemical families are arranged in vertical groups. Periodic Tables can indicate the chemical symbol, atomic number, atomic mass, ion charge, density, and other information about each element.

Elements, Atoms, and the Atomic Theory CHAPTER Elements, Atoms, and the Atomic Theory 6 Activity Draw your own Classification of Matter chart in your notebook. Use the example below as a guide. Under each heading, write at least three common examples of each form of matter. See pages 149–150 in the textbook for clarification and a description of each heading if needed.

Elements, Atoms, and the Atomic Theory CHAPTER Elements, Atoms, and the Atomic Theory 6 Key Ideas Matter is made of atoms. Atoms have a structure that determines their properties. The Periodic Table organizes elements in different ways.