Notes 2A: Matter Important vocabulary. There will be a quiz on the words and concepts in red.

Matter: anything that has mass and volume. Matter: anything that has mass and volume. Two types of matter: Two types of matter: Substances Substances Mixtures Mixtures

What is a substance? What is a substance? Only 1 chemical is present. Only 1 chemical “formula”. Is there anything to watch out for Yes… if a chemical is “dissolved in water”…you are not working with a substance. Why? Because water is a substance by itself and the chemical is a different substance by itself. Combined together you have a mixture!

What is a mixture? What is a mixture? Two or more substances combined together. The original substances still have their original properties. Ex: cinnamon mixed with sugar tastes like a topping we call “cinnamon sugar”. If you would un-mix a mixture, you would still have the original substances.

There are 2 different types of substances. There are 2 different types of substances. “Elements” and “Compounds”. Element: Element: Its atoms all have the same number of protons in their nucleus. 118 elements: 94 occur naturally on earth. The remaining are “synthetic” (made my man). They are listed in order of their atomic number across the rows and down the columns of the periodic table.

Elements are referred to by their name or by their “element’s symbol”. Elements are referred to by their name or by their “element’s symbol”. An element’s symbol is correctly written as a capital letter followed by 1 or 2 lower case letters. An element’s symbol is correctly written as a capital letter followed by 1 or 2 lower case letters.

Each symbol that you see written on an element’s periodic table square may represent 1 atom of that element. Each symbol that you see written on an element’s periodic table square may represent 1 atom of that element. Unfortunately each symbol may also represent more than 1 atom of that element. Unfortunately each symbol may also represent more than 1 atom of that element. Especially confusing is that some atoms occur naturally as molecules. Especially confusing is that some atoms occur naturally as molecules.

Examples: Examples: Nickel, a solid metal: Nickel, a solid metal: Ni = a single atom Ni = a single atom Ni = many atoms chemically joined together Ni = many atoms chemically joined together Neon, a gas. Neon, a gas. Ne = a single atom Ne = a single atom Ne = many atoms each independent of the others Ne = many atoms each independent of the others

Chlorine, a gas: Chlorine, a gas: Cl = a single atom. Cl = a single atom. Cl = many single atoms of chlorine; but, single atoms of chlorine won’t stay single for more than a fraction of a second. In other words, “Cl” isn’t a good representation of what exists! Cl = many single atoms of chlorine; but, single atoms of chlorine won’t stay single for more than a fraction of a second. In other words, “Cl” isn’t a good representation of what exists! A molecule of chlorine gas: Cl 2 A molecule of chlorine gas: Cl 2 The 2 in the subscript position means that there are 2 atoms of chlorine (connected through a chemical bond) in every molecule of chlorine gas. The 2 in the subscript position means that there are 2 atoms of chlorine (connected through a chemical bond) in every molecule of chlorine gas. Cl 2 also represents many molecules of chlorine gas, each independent of the others. Cl 2 also represents many molecules of chlorine gas, each independent of the others.

Since chlorine (as a gaseous element) only ever occurs in the form of a molecule, then we say the symbol for chlorine when in “elemental form” is Cl 2. Since chlorine (as a gaseous element) only ever occurs in the form of a molecule, then we say the symbol for chlorine when in “elemental form” is Cl 2.

Carbon, a solid non-metal: Carbon, a solid non-metal: C = a single atom of carbon C = a single atom of carbon C = many single atoms chemically joined together. C = many single atoms chemically joined together. Ex: fireplace “soot”. Ex: fireplace “soot”. Ex: graphite in a pencil. Ex: graphite in a pencil. Ex: diamond. Ex: diamond. C 60 = 1 molecule of buckminsterfullerene. C 60 = 1 molecule of buckminsterfullerene. C 60 = many molecules of buckminsterfullerene C 60 = many molecules of buckminsterfullerene When 1 chemical element is known to be found naturally in different forms, all in the same state (either solid, liquid, or gas), we say that this chemical element exists in “allotropic forms” (or we say: the element has “allotropes”. When 1 chemical element is known to be found naturally in different forms, all in the same state (either solid, liquid, or gas), we say that this chemical element exists in “allotropic forms” (or we say: the element has “allotropes”.

Oxygen: a gas that exists in allotropic forms. Oxygen: a gas that exists in allotropic forms. O 2 = oxygen gas that we need to stay alive. O 2 = oxygen gas that we need to stay alive. O 3 = ozone. O 3 = ozone. Ozone in the earth’s stratosphere protects us from harmful uv radiation Ozone in the earth’s stratosphere protects us from harmful uv radiation Ozone at nose level may cause respiratory distress. Ozone at nose level may cause respiratory distress.

If a chemical substance isn’t an “element”, what is it? If a chemical substance isn’t an “element”, what is it? A “compound”. A “compound”. Compounds contain atoms of 2 or more different elements that are chemically joined together. Compounds contain atoms of 2 or more different elements that are chemically joined together. We can’t separate the atoms that are joined together in a compound without reacting the compound with another chemical. We can’t separate the atoms that are joined together in a compound without reacting the compound with another chemical.

We refer to a compound by its “chemical formula”: We refer to a compound by its “chemical formula”: CO 2 is the chemical formula for carbon dioxide. CO 2 is the chemical formula for carbon dioxide. A number written as a “subscript” multiplies the 1 atom that the subscript immediately follows. A number written as a “subscript” multiplies the 1 atom that the subscript immediately follows. # carbon atoms = 1 # carbon atoms = 1 # oxygen atoms =2 # oxygen atoms =2

H 2 O is the chemical formula for water. H 2 O is the chemical formula for water. # H atoms = 2 # H atoms = 2 # O atoms = 1 # O atoms = 1 C 12 H 22 O 11 is the chemical formula for table sugar. C 12 H 22 O 11 is the chemical formula for table sugar. # C atoms = 12 # C atoms = 12 # H atoms = 22 # H atoms = 22 # O atoms = 11 # O atoms = 11

When parentheses are present in a chemical formula. When parentheses are present in a chemical formula. A number written as a “subscript” following parentheses, multiplies each atom within the parentheses. A number written as a “subscript” following parentheses, multiplies each atom within the parentheses. Al 2 (CO 3 ) 3 Al 2 (CO 3 ) 3 # Al atoms = 2 # Al atoms = 2 # C atoms = 3 # C atoms = 3 # O atoms = 3 x 3 = 9 # O atoms = 3 x 3 = 9