Chemistry is the study of Elements When you change the number of protons of any atom, you get a different element! Chemistry is the study of Elements Elements are the specific examples of different atoms. Ex: Hydrogen, Oxygen, Gold Atoms are the smallest piece of matter. All things we know are made of trillions of atoms in different combinations (including us). No two different elements have the same atom. What makes each different are the numbers of their parts. The type of atom is determined by the number of Protons called: “Atomic Number” (this is found on the periodic Table) For example: Lithium is an element with 3 protons in its nucleus. If it lost one, it would no longer be Lithium, it would be called Helium! If Lithium got a new proton (added to it’s original 3), it would now be called Beryllium! Every element is identified by the number of protons in it’s nucleus. It is IMPOSSIBLE to have two different elements with the same number of protons!!!

Quick review of the parts of an atom: Atoms will usually have the same number of Protons & Electrons Quick review of the parts of an atom: Electrons: Negative charge This shaded area includes the protons and neutrons. And we call it the nucleus! Neutrons: No charge Protons: Positive Charge (“Atomic Number”) If there are 4 + charges (protons), then there will usually be 4 – charges (electrons) and the charge will be “neutral” Think: What Element is this? 2 Protons = Helium Atom!!!

Bohr Models Shell 1: 2 e- Shell 2: 8 e- Shell 3: 8 e- Shell 4: 18 e- - Neils Bohr was able to discover that electrons (e-) are located in different “shells” (like a ring) around the nucleus. Each shell can only hold a certain number of electrons before it is “full” “Valence” Rule: All atoms want a full outer shell of e- Shell 1: 2 e- Shell 2: 8 e- Shell 3: 8 e- Shell 4: 18 e- Etc…(7 total shells possible) Element: Nitrogen A: 3! 5+3=8 Q: How many more e- COULD fit on the outer shell?

Periods Each row is called a “period” The elements in each period have the same number of shells 1st Period = 1 Shell 2nd Period = 2 Shells 3rd Period = 3 Shells 4th Period = 4 Shells www.chem4kids.com

Groups Group 8 = 8 electrons Group 1 = 1 electron Except for He, it has 2 electrons Group 2 = 2 electrons Each column is called a “group” 3, 4, 5, 6, 7 Each element in a group has the same number of electrons in their outer orbital, also known as “shells”. The electrons in the outer shell are called “valence electrons” www.chem4kids.com

Transition Metals Transition Metals have slightly different rules for shells and valence electrons. This is something you will learn about in High School Chemistry. www.chem4kids.com

EX: The elements in group I all react the same with water!!! The P.T. is also separated into the types of Elements: The “types” of elements are determined by their chemical and physical properties!!! = Metal Elements = Semi-Metal Elements =Non-Metal Elements (usually gases) EX: The elements in group I all react the same with water!!! Metals (+ valences) Get Rid of Electrons “+” extra e-

Determine the number of shells and the number of valence electrons for: Carbon - C 2nd Period = 2 shells 4th Group = 4 valence electrons www.chem4kids.com

First, get to know this key. It explains all the symbols on the P.T.E. The periodic table of elements is an organized chart of all known elements. There are tons of great patterns that explain how chemistry works once you get the hang of it!

Periods: There are seven total! The horizontal “rows” are called “periods” 1 2 3 Periods: There are seven total! 4 5 6 7

1 The vertical “columns” are called “Groups” 8 2 3 4 5 6 7 Groups: We need to know 8 total

You can use the P.T. to make your atomic models: +1 Full Shell One +2 +3 +/-4 -3 -2 -1 Shell Two Shell Three Shell Four Shell Five Shell Six Shell Seven

Hydrogen The hydrogen square sits atop Family AI, but it is not a member of that family. Hydrogen is in a class of its own. It’s a gas at room temperature. It has one proton and one electron in its one and only energy level. Hydrogen only needs 2 electrons to fill up its valence shell.

Alkali Metals The alkali family is found in the first column of the periodic table. Atoms of the alkali metals have a single electron in their outermost level, in other words, 1 valence electron. They are shiny, have the consistency of clay, and are easily cut with a knife.

Alkaline Earth Metals They are never found uncombined in nature. They have two valence electrons. Alkaline earth metals include magnesium and calcium, among others.

Transition Metals Transition Elements include those elements in the B families. These are the metals you are probably most familiar: copper, tin, zinc, iron, nickel, gold, and silver. They are good conductors of heat and electricity.

Boron Family The Boron Family is named after the first element in the family. Atoms in this family have 3 valence electrons. This family includes a metalloid (boron), and the rest are metals. This family includes the most abundant metal in the earth’s crust (aluminum).

Carbon Family Atoms of this family have 4 valence electrons. This family includes a non-metal (carbon), metalloids, and metals. The element carbon is called the “basis of life.” There is an entire branch of chemistry devoted to carbon compounds called organic chemistry.

Nitrogen Family The nitrogen family is named after the element that makes up 78% of our atmosphere. This family includes non-metals, metalloids, and metals. Atoms in the nitrogen family have 5 valence electrons. They tend to share electrons when they bond. Other elements in this family are phosphorus, arsenic, antimony, and bismuth.

Oxygen Family Atoms of this family have 6 valence electrons. Most elements in this family share electrons when forming compounds. Oxygen is the most abundant element in the earth’s crust. It is extremely active and combines with almost all elements.

Halogen Family The elements in this family are fluorine, chlorine, bromine, iodine, and astatine. Halogens have 7 valence electrons, which explains why they are the most active non-metals. They are never found free in nature. Halogen atoms only need to gain 1 electron to fill their outermost energy level. They react with alkali metals to form salts.

Noble Gases Noble Gases are colorless gases that are extremely un-reactive. One important property of the noble gases is their inactivity. They are inactive because their outermost energy level is full. Because they do not readily combine with other elements to form compounds, the noble gases are called inert. The family of noble gases includes helium, neon, argon, krypton, xenon, and radon. All the noble gases are found in small amounts in the earth's atmosphere.

Rare Earth Elements The thirty rare earth elements are composed of the lanthanide and actinide series. One element of the lanthanide series and most of the elements in the actinide series are called trans-uranium, which means synthetic or man-made.

Li Lewis Dot models Li Li Lewis realized that the most important e- for modeling are the “Valence” electrons. These are the e- that are available for bonding! (they are found on the outer shell!) The Li atom is considered “full” with 10 e-. The final product looks like this: Li Valence electron Valence electron Li Li +1 valence Rule: Imagine an invisible square Bohr Model Rule: Only 2 e- at most are drawn on each side of the “square”

Lewis Dot Models Valence Electrons To help you see it, we need to learn the Period Table of Elements You can see all these different Elements “Dot” models It may look like chaos, but there really is a pattern here: