Elements & Atoms

1. Elements & Atoms Created by G.Baker www.thesciencequeen.net

2. Learning Activity 2cde: Intro to Bohr Model and Lewis Dot Structures Learning Targets: I can... 2c) Compare and contrast the Bohr model and modern scientific model of an atom emphasizing the evidence that supports each model and the limitations of each model. (DOK 1-2) 2d) Draw the Bohr model, Lewis dot structure, and electron configuration of simple atoms (# 1-20) (DOK 1) 2e) Describe how the periodic table is organized in terms of atomic number, atomic mass, and valence electrons. (DOK 1)

3. An atom refresher • Matter is anything that takes up space and has mass. • All matter is made of atoms • Atoms are the building blocks of matter, sort of how bricks are the building blocks of houses.

4. An atom refresher An atom has three parts: • Proton = positive • Neutron = no charge • Electron = negative • The proton & neutron are found in the center of the atom, a place called the nucleus. • The electrons orbit the nucleus. Picture from http://education.jlab.org/qa/atom_model_03.gif

5. Graphic from http://education.jlab.org/atomtour/fact2.html

6. Elements • Elements are the building blocks of all matter. • The Periodic Tableis a list of all of the elements that can build matter. It’s a little like the alphabet of chemistry. • The periodic table tells us several things…

7. Periodic Table Atomic Number: Number of protons and also the number of electrons in an atom of an element. 8 O Element’s Symbol:An abbreviation for the element. Oxygen Element’s Name Atomic Mass/Weight: Number of protons + neutrons. 16

8. Name1/15/14Period___ Atoms and Elements Part 2 • Students will diagram both the Bohr model of the atom and Lewis Dot Diagrams by taking notes. Objective:

9. Folder Check! • Have it out next to you while you take notes. Created by G.Baker www.thesciencequeen.net

10. Atom Models There are two models of the atoms we will be using in class. • Bohr Model • Lewis Dot Structure

11. Bohr Model • The Bohr Model shows all of the particles in the atom. • In the center are circles. Each circle represents a single neutron or proton. Protons should have a plus or “p” written on them. Neutrons should be blank or have an “n.” • In a circle around the nucleus are the electrons. Electrons should have a minus sign or an e. - + + -

12. Rules for Electrons • You can’t just shove all of the electrons into the first orbit of an electron. • Electrons exist in shells or energy levels. • Also called orbitals • Only so many can be in any certain shell. • The electrons in the outer most shell of any element are called valance electrons.

13. Nucleus 1st shell 2nd shell 3rd shell 8 Adapted from http://www.sciencespot.net/Media/atomsfam.pdf

14. Electron Shells • Only two electrons (e-) will fit in the first shell. • Only eight electrons will fit in the second and third shells.

15. Name1/15/14Period___ Atoms and Elements Part 2 • Students will diagram both the Bohr model of the atom and Lewis Dot Diagrams by taking notes. Objective:

16. Rules for Drawing an Atom: • Determine the number of protons (atomic number) • Determine the number of neutrons (Atomic mass – atomic number) • Determine the number of electrons (atomic number) 3 Li Lithium 7

17. So let’s try it…. Protons = 3 3 Li Lithium 7 - + + + - - Electrons = 3 2 in the 1st shell, 1 in the 2nd shell Atomic Mass = 7 Neutrons = 4 (7-3=4)

18. What should it look like on paper? e- e- 3 p+ 4 n e- How many valence electrons are in Lithium?

19. Stable Atoms (Magic Number 8!) • Atoms with a full outer shell (8 e-) are stable • They don’t react or bond with any other element Ex: He = 2 valence electrons in the first shell Ne = 8 valence electrons in the second shell Ar = 8 valence electrons in the third shell These are the Noble Gasses!

20. - - - - - - - - + + + + + + + + Lewis Dot Diagram Bohr Model • The Lewis Dot Structure is a bit different from the Bohr model. • It only shows the element symbol and it’s valence electrons. • • O • • • • Lewis Dot Diagram

21. How to write a Lewis Dot diagram: Try Lithium: • How many valence electrons? • Write the symbol. • Start on the right. • Go clockwise. • Fill in up to two dots on a side. Li

22. How to… Try Chlorine: • How many valence electrons? • Write the symbol. • Start on the right. • Go clockwise. • Fill in up to two dots on a side. Cl

23. Name1/15/14Period___ Atoms and Elements Part 2 • Students will diagram both the Bohr model of the atom and Lewis Dot Diagrams by taking notes. • Students will practice the Bohr Model and pulling information from the Periodic Table by doing a worksheet. Objective:

24. Your activity… • Using the beans (Lentils are electrons, Lima Beans are protons, and kidney beans are neutrons), create a Bohr model , and then a Lewis dot structure model of each of the first 20 elements. After you have created each model, draw each model on your chart. • Hint to make a chart, use a burrito fold, then fold the top down by 1 ½ inches. Unfold, you now have 3 columns. Label the columns: element, Bohr model, Lewis Dot.

25. What are elements? • Elements are the alphabet to the language of molecules. • To make molecules, you must have elements. • Elements are made of atoms. While the atoms may have different weights and organization, they are all built in the same way. Information & picture from Chem4kids at http://www.chem4kids.com/files/atom_structure.html