1. SCIENCE 9 MODELS OF THE ATOM

2. ALL ATOMS ARE NOT CREATED EQUAL Atoms can vary from one to the next of the same element in the number of neutrons they have in their structure Two atoms that have the same number of protons but different number of neutrons are called isotopes Carbon has three isotopes: carbon-12 6 protons, 6 neutrons, 6 electrons carbon-13 6 protons, 7 neutrons, 6 electrons carbon-14 6 protons, 8 neutrons, 6 electrons

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4. CHARGED ATOMS ARE IONS Atoms are capable of gaining and losing electrons When they lose or gain electrons, they are called ions The number of protons determines the identity of an element The number of electrons can change and the element still remain the same It is more common for atoms to have more or less electrons than protons than for them to be equal to each other

5. EXAMPLE sodium atom (Na) 11 protons, 12 neutrons, 11 electrons sodium ion (Na 1+ ) 11 protons, 12 neutrons, 10 electrons Protons are positively charged and electrons are negatively charged Ions have an unequal number of protons and electrons

6. ELECTRONS DETERMINE CHEMICAL COMBINATIONS Neils Bohr attempted to make a model of an atom to help explain the chemical behavior of atoms and ions Protons and neutrons are found in a nucleus Outside the nucleus are electrons in pathways called orbits Electrons have energy and can move from one orbit to another The further an electron is from the nucleus, the more energy it has The number of electrons found in the first three orbits is 2, 8, 8

7. BOHR MODEL OF THE ATOM

8. ENERGY AND ELECTRONS When an atom is energized, electrons move from a lower energy level to a higher one The electrons move further away from the nucleus This is called an excited state When the electron releases its energy and moves back to the orbit with which is came, it is said to be in a ground state The number of electrons that move from one orbit to another coupled with the orbits within which they move give off specific colors of light

9. ATOMIC SPECTRA Every element on the periodic table, when given energy, produces a unique spectra of light This is how scientists identify unknown elements