1. Chemistry Do Now
Directions: Take out a sheet of notebook (Do Now sheet) and set it up as instructed. Answer the following question. (5 minutes).
Why are atoms electrically neutral?
How does an atom become a positively charged ion?
How does an atom become a negatively charged ion?
Gaining 1 or more electrons makes an atom have a ______________ charge.
Losing 1 or more electrons makes an atom have a ____________ charge.

2. Chemistry Do Now Key
Why are atoms electrically neutral? The #protons equals the #electrons.
How does an atom become a positively charged ion? If it loses 1 or more electrons
How does an atom become a negatively charged ion? If it gains 1 or more electrons
Gaining 1 or more electrons makes an atom have a negatively charge.
Losing 1 or more electrons makes an atom have a positively charge.

3. Objective
Students will know the basic unit of matter by taking notes on the atom, watching a video on atoms, building an atom and analyzing the Periodic Table of Elements.
Mastery Level: 75% or better

4. Homework
Directions: Compare and contrast the following. How are they similar and how are they different?
1) Sodium atom (Na) and sodium ion (Na+1)
2) Chlorine atom (Cl) and chloride ion (Cl-1)

5. Structure of an Atom

6. What Is an Atom?
Atoms are often referred to as the building blocks of matter.
Each element on the periodic table is composed of one type of atom and cannot be broken down into a simpler substance.
Structure of the atom. (n.d.). Retrieved from

7. What Is an Atom?
Atoms are composed of smaller subatomic particles such as the proton, neutron, and electron.
Atoms contain a nucleus surrounded by an electron cloud that consists of one or more energy levels.

8. Inner Structure of an Atom
Nucleus - Small, dense, positively charged center of the atom which contains most of the atom’s mass

9. Inner Structure of an Atom
The nucleus contains the following subatomic particles:
Protons - positively (+) charged particles
Neutrons - particles that have no charge (neutral), but contribute to the atom’s mass

10. Outer Structure of an Atom
Electron cloud - an area around the nucleus where electrons are likely to be found orbiting the nucleus in several energy levels

11. Outer Structure of an Atom
The electron cloud contains several energy levels
Electrons - negatively (-) charged particles located in specific energy levels surrounding the nucleus

12. Outer Structure of an Atom
Multiple energy levels in the electron cloud completely surround the nucleus.
Electrons follow a specific order to fill the energy levels.
Maximum of 2 electrons
Nucleus
Maximum of 8 electrons
Maximum of 8 electrons*
*Applies to the first 18 elements only

13. Outer Structure of an Atom
The electrons in the outermost energy level are called valence electrons
We will go into more detail about the importance of valence electrons in our next unit.

14. Decoding Atom Information from the Periodic Table
Carbon 6
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Atomic Number
Atom’s
Symbol
Atom’s Name
Atomic
Mass

15. Decoding Atom Information from the Periodic Table
Atomic number
# of protons = # of electrons 6 C
Carbon
Atomic mass = # of protons plus the # of neutrons
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16. Atom Characteristics
The number of protons in the nucleus is the atomic number of that atom. Protons are used to identify elements.
The atomic number represents the number of protons (+) and is equal to the number of electrons (-).

17. Atom Characteristics
The atomic mass is the mass of the protons plus the mass of the neutrons.
Atomic mass is recorded in atomic mass units (amu).
Protons and neutrons each are given an amu of 1.
Electrons have a mass of nearly zero.
The mass of 1 proton or 1 neutron is equivalent to approximately electrons.
Structure of the atom. (n.d.). Retrieved from