Name: Date: Pd: Unit 2: Atomic Structure: Isotopes Guided Notes. Positively charged (+1). Found in the nucleus.

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1 _ Atoms: The Building Blocks of everything? Unit 2: Atomic Structure: Isotopes Guided Notes An atom consists of a An atom is the smallest unit of an element that is possible. All the matter around us is made of individual atoms. Sometimes different atoms join together to form new substances. o Two Hydrogen Atoms will join an Oxygen atom and form water (H 2O). In this sense atoms are the building blocks of matter but atoms are usually made up of three smaller particles and two of those particles are made up of even smaller particles. o So an atom is not a building block of matter. Nucleus (protons and neutrons) Electrons in space about the nucleus. Nucleus Protons Neutrons Positively charged (+1). Found in the nucleus. Neutral particle in an atom. Found in the nucleus. Electron Cloud Electrons Negatively charged particle (-1). Found outside the nucleus. The atom is mostly empty space o Most of the mass of an atom is in the Protons and Neutrons are roughly equal in mass but a neutron is ever so bigger than a proton. Therefore we say the each has a mass of amu (atomic mass unit) A proton (and a neutron) are about 1800 times as massive as an electron. Electron Proton Neutron Proton Electrons Travel around the nucleus in the electron cloud which is mostly empty space In a atom the number of electrons is the number of protons since that is the only way to have a net charge of.

2 PART I: ATOM SCREEN Go to the website: phet.colorado.edu. Click on HTML5 simulations on top right of screen and choose the Build an Atom simulation ( Click on the Atom Explore Protons: icon 1. Click the green signs to show Element. 2. Drag one proton and one electron to the atom. Record the Element: 3. Drag an additional proton to the model. Record the Element: 4. Drag an additional proton to the model. Record the Element: 5. What happened when additional protons were placed in the atom? Explore Neutrons: 1. Click to reset the simulation 2. Click on at the bottom of the screen 3. Click the green + sign to show Symbol 4. Drag three protons, three neutrons, and three electrons to the model. Record the Symbol:. 5. Drag an additional neutron to the model. Record the Symbol:. 6. Drag an additional neutron to the model. Record the Symbol:. 7. What happened when additional neutrons were placed in the atom? Explore Electrons: 1. Click to reset the simulation 2. Click on at the bottom of the screen 3. Click the green + sign to show Symbol 3. Drag four protons, five neutrons, and three electrons to the model. Record the Symbol:. 4. Drag an additional electron to the model. Record the Symbol:. 5. Drag an additional electron to the model. Record the Symbol:. 6. What happened when additional electrons were placed in the atom? Activity Questions 1. What particle determines what element you have?

3 2. What particle(s) can change without changing the identity of an element? Key Vocabulary Isotope atoms of the same element that have the same number of but a different number of Ions atoms of the same element that have the same number of but different number of All elements consist of naturally occurring isotopes and artificially produced isotopes The isotopes of an element have: Chemical Properties (this is because they have the same numbers of protons and electrons and subatomic particles are responsible for chemical behavior) Physical Properties (different mass and different number of neutrons) Use the isotope symbol to determine the number of subatomic particles present in AN ATOM of the isotope Use the periodic table to determine the number of subatomic particles present in an atom of the MOST NATURALLY ABUNDANT isotope for that element There are three types of hydrogen but the vast majority of hydrogen is protium. The atomic mass is a weighted average of all the types of hydrogen. So if you had a bag filled with hydrogen gas, it would have all three types but most of it would be protium. Therefore, we the average atomic mass to the nearest whole number.

4 How to Read a Periodic Table Tile 11 Na Sodium PART II: ISOTOPES A NEUTRAL CARBON ATOM HAS HOW MANY OF EACH PARTICLE? Protons: Neutrons: Electrons: The 6 on the top is the atomic number of carbon and that is also the number of protons any atom of carbon must have. The on the bottom is the average atomic mass and is also the number of protons and neutrons in average carbon atom. Six of those 12 must be protons because Carbon has an atomic number of 6 so what is left over are neutrons. An electrically neutral atom must have an overall charge of 0. This means the total number of electrons (-1 charge) must be equal to the number of protons (+1 charge).

5 Proton Number = Atomic Number. Neutron Number: Atomic Mass ( ) minus Atomic Number. (or bottom minus top) Electron Number = Proton Number (if Neutral) Protons: Neutrons: Electrons: Protons: Neutrons: Electrons: Concept Check! Why do we only consider the number of neutrons and protons when determining the mass number of an atom?

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7 Isotope Classwork Practice 1 Use your Periodic Table to help you complete the following tables Element Element Atomic Atomic Mass # of Electrons # of Protons # of Neutrons Name Symbol Number Hydrogen Oxygen Sulfur Gold Lead Element Element Atomic Atomic Mass # of Electrons # of Protons # of Neutrons Name Symbol Number He Practice 2 Element/Isotope Element Atomic Atomic Mass/ # of Electrons # of Protons # of Neutrons Name Symbol Number Mass Number Fluorine Argon -39 Neon-20 Neon-21

8 Neon-22 Element/Isotope Name Element Symbol Atomic Number Atomic Mass # of Electrons # of Protons # of Neutrons Hydrogen-1 Hydrogen-2 Hydrogen-3-35 Cl Chlorine-37 Carbon-12 Carbon Exit Ticket Atom 1 Atom 2 Relationship between atom 1 and atom 2 12 Isotopes 6C 6C Carbon Isotopes 6C Argon-40 Argon-41 Isotopes 11 5 B An atom with 13 protons and 13 neutrons Boron-10 An atom with 14 protons and 13 neutrons Isotopes Isotopes