The Chemical Nature of Matter 7.P.2A.4 Notes

What is MATTER? Anything that has mass and takes up space Matter is composed of extremely small particles, too small to be seen with a classroom microscope, called atoms.

What is not MATTER? Light and Sound Sound waves

What is an ELEMENT? Pure substances that cannot be changed into simpler substances. Composed of one kind of atom Examples: Hydrogen, Oxygen, Carbon, Nitrogen, Helium Ex. Silver, oxygen, hydrogen, helium, and aluminum There are as many types of elements as there are atoms more than 100.

What is a COMPOUND? Pure substance that consists of two or more different types of elements chemically bonded together Only changed into simpler substances called elements by chemical changes One way that two or more atoms can combine is to form a molecule. Compound can have very different properties from the elements that make up that compound Ex. Table Salt is safe to eat, the individual elements that go into making it are poisonous

What is a MOLECULE? When two or more atoms bond together, or combine they make a particle called a molecule. Oxygen atom Hydrogen atoms A molecule is the smallest amount of a substance made of combined atoms that is considered to be that substance. Ex. Break water apart Molecules can be made up of different numbers of atoms. Molecules made up of diferrent numbers of the same atom are different substances. Water Molecule

The two types of chemical bonds are Ionic and Covalent Bonds Ex. Dust particles bouncing off air molecules Ex. When drop food coloring in water, eventually water molecules will cause the food coloring to spread throughout the water. Ex. Molecules in tables can’t be seen easily in motion, but constantly moving by shaking back and forth, or by twisting, even thought hey stay in the same place.

Types of Chemical Bonds An ionic bond is formed when metals react with nonmetals, electrons are transferred from the metals to the nonmetals. When two or more nonmetals form compounds, they share electrons through covalent bonds. These compounds are called covalent compounds. One way that two or more atoms can combine is to form a molecule. Compound can have very different properties from the elements that make up that compound Ex. Table Salt is safe to eat, the individual elements that go into making it are poisonous

Chemical Formulas Chemical formulas use element symbols from the periodic table and numerical subscripts to depict the name and number of atoms of each element in the compound. One way that two or more atoms can combine is to form a molecule. Compound can have very different properties from the elements that make up that compound Ex. Table Salt is safe to eat, the individual elements that go into making it are poisonous

Chemical Formulas In a chemical formula, the numbers as subscripts show how many of each kind of atom are in the compound. One way that two or more atoms can combine is to form a molecule. Compound can have very different properties from the elements that make up that compound Ex. Table Salt is safe to eat, the individual elements that go into making it are poisonous

Chemical Formulas The subscript is written to the lower right of the element symbol. If no subscript is written, only one atom of that element is part of the compound. One way that two or more atoms can combine is to form a molecule. Compound can have very different properties from the elements that make up that compound Ex. Table Salt is safe to eat, the individual elements that go into making it are poisonous

Diatomic Molecules N2, O2, F2, Cl2, Br2, I2, and H2 are diatomic molecules where all of the atoms of the molecule are the same element. One way that two or more atoms can combine is to form a molecule. Compound can have very different properties from the elements that make up that compound Ex. Table Salt is safe to eat, the individual elements that go into making it are poisonous

Ionic Bonds Ionic bonds are formed when metals and nonmetals chemically bond to form a new substance. In ionic bonds, electrons are transferred from the metals to the nonmetals. Mg N NONMETAL METAL 3 2 SUBSCRIPTS

Covalent Bonds Covalent bonds are formed when nonmetals bond with other nonmetals. In covalent bonds, electrons are shared.