February Valentine’s Day-10, 2010 Objective: SWBAT calculate numbers of protons, neutrons, and electrons given mass SWBAT draw Bohr models for elements 1-20 Catalyst: Draw a picture of Niels Bohr’s model looks like? Find element Zn. How many protons does it have? Neutrons? Electrons? Agenda Catalyst HW Review Atomic Math Practice! Bohr Models Practice! Exit Question So atoms are the smallest thing in the universe NO!....atoms are the smallest unit of an element Based on the experiments we learned about, what 3 things are atoms made of? Subatomic Particles Key Point #1: The three main subatomic particles are… Protons Neutrons Electrons Subatomic Particles Subatomic Particle Protons Neutrons Electrons Location Relative means compared to others Relative Mass NUCLEUS 1 amu NUCLEUS 1 amu OUTSIDE NUCLEUS 1/1840 amu (virtually zero!) Relative Charge 1+ NEUTRAL 1- Atomic Math! Key Point #2: Atomic math helps us to find… Number of protons Number of neutrons Number of electrons This helps us distinguish atoms from each other! Atomic Number is an Element’s ID Number Who was #23 on the Chicago Bulls? Who is #23 on the Cleveland Cavs? Who is #9 on the Saints? Like your social security number or a professional athlete’s jersey number, it identifies that element How is C different from Ca? Key Point #3: The type of element an atom is depends on the number of protons in the nucleus Atomic Number = Number of Protons The atomic number is the whole number in the periodic table pREVIEW of the Periodic Table Atomic Number Element Symbol Atomic Mass Not all C’s are created equal Key Point #4: Two atoms of the same element that have different numbers of neutrons are called isotopes Although every carbon atom has 6 protons not all of them are identical The number of neutrons in the nucleus can be different Thought Exercise Imagine you have a pile of fruit. There are watermelons, cantaloupes and grape. Each watermelon weighs 1 lb Each cantaloupe weighs 1 lb Each grape weighs 0.001 lbs If you wanted to find the mass of the whole fruit pile, which two fruits could you add together to find the total mass? Why can you ignore one of the fruits? How else are isotopes different? Look back at the relative masses of the subatomic particles Which particles affect the mass of an atom? Based on your answer above, finish the equation below: PROTONS NEUTRONS Atomic Mass = ___________+___________ Atomic Mass Practice Question #1 How many protons does a Phosphorus (P) atom have? Question #2 A Fluorine (F) atom has 10 neutrons. What is its atomic mass? Atomic Shorthand Each element has a name and can be abbreviated with one or two letters This is called the atomic symbol The mass is written in the upper left-hand corner of the atomic symbol 12C These or carbon-12 mean the atom is Carbon and its atomic mass is 12 How many protons and neutrons does this atom have? More Practice Question #3 Determine the number of protons and neutrons in the following isotopes: 20Ne and Ne-22 Question #4 Which element has an atomic mass of 15 and has 7 neutrons? What if it had 8 neutrons and the same mass as above? Atoms Key Point #5: All elements have no charge (neutral) in their pure form This PROTONS (+) is means that the number of ____________ ELECTRONS (-) equal to number of _____________. How many electrons does Oxygen have? How many electrons does Calcium have? Atomic Math Bylaws 1. 2. 3. PROTONS Atomic number = number of _______________. Number of protons = number of ELECTRONS _______________(in a neutral atom). PROTONS Atomic mass = number of _________________ NEUTRONS plus the number of _________________. Protons, Neutrons, and Electrons For each of the following atoms determine the number of protons, neutrons, and electrons, and the atomic mass. Hydrogen-1 Copper-63 2H 65Cu Carbon-12 Cesium-133 13C Uranium-234 14C 235U 12O 238U 13O 9Be Oxygen-14 33S Bohr Models of Atoms Bohr Models show electrons floating around the nucleus in specific orbits. 16 p+ 16 no Sulfur: 16 protons 16 neutrons 16 electrons Steps to Making a Bohr Model 1. 2. 3. 4. 5. 6. 7. Determine protons, neutrons, and electrons are in the atom Draw the nucleus (circle) with # p+ and # no inside Draw the first energy level (circle around nucleus) and draw up to 2 dots (electrons) If needed, draw second energy level (second circle) and draw up to 8 dots (electrons) If needed, draw third energy level (third circle) and draw up to 8 dots (electrons) If needed, draw fourth energy level (fourth circle) and draw up to 2 dots (electrons) Continue drawing energy levels as needed (draw up to 32 dots on each) Got it? Let’s draw the Bohr model for this element. Practice Time Draw Bohr Models for the first 20 elements on your notes sheet We will do a few together first Remember, find the number of protons, electrons, and neutrons first…then get drawing! Work Time Complete the Atomic Structure worksheet Check your Atomic Math! Exit Question 1. Ruthenium has an atomic number of 44. It has an atomic mass of 101. How many protons, neutrons, electrons does a neutral atom of Ruthenium have?