1. Unit 3: The Atom

2. Atoms All matter is made of very tiny particles All matter is made of very tiny particles These particles have the same properties as the matter has These particles have the same properties as the matter has

3. Parts of the Atom Subatomic Particles – smaller than an atom Subatomic Particles – smaller than an atom Proton Proton Neutron Neutron Electron Electron

4. Subatomic Particles Protons Protons Positive charge Positive charge Each one has a charge of +1 Each one has a charge of +1 Located in the nucleus Located in the nucleus Each one has a mass of 1amu (atomic mass unit) Each one has a mass of 1amu (atomic mass unit)

5. Subatomic Particles Neutrons Neutrons No charge No charge Located in the nucleus Located in the nucleus Each one has a mass of 1amu (atomic mass unit) Each one has a mass of 1amu (atomic mass unit)

6. Subatomic Particles Electrons Electrons Negative charge Negative charge Each one has a charge of -1 Each one has a charge of -1 Located in the space around the nucleus Located in the space around the nucleus Each one has a mass of about 0.0006amu (atomic mass unit) Each one has a mass of about 0.0006amu (atomic mass unit)

7. The Atom

8. The nucleus has protons and neutrons The nucleus has protons and neutrons Positively charged Positively charged The electron cloud has electrons The electron cloud has electrons Negatively charged Negatively charged The number of protons equals the number of electrons in a neutral atom The number of protons equals the number of electrons in a neutral atom

9. Periodic Table The periodic table gives us lots of information about the elements. The periodic table gives us lots of information about the elements. 1 H Hydrogen 1.008 Atomic Number Element Symbol Element Name Average Atomic Mass

10. Symbol Practice For the element name, give the symbol. HeliumCarbonSulfurOxygenMagnesium

11. Element Practice For the symbol, give the element name. LiNArAlNa

12. Atomic Number Atoms of different elements are different Atoms of different elements are different All protons and neutrons are identical to each other All protons and neutrons are identical to each other The number of protons in the nucleus explains the difference The number of protons in the nucleus explains the difference The number of protons in the nucleus is the atomic number of an element The number of protons in the nucleus is the atomic number of an element

13. Atomic Number The atomic number identifies the element The atomic number identifies the element Like DNA for an element Like DNA for an element Examples: Examples: Hydrogen atoms and only hydrogen atoms have 1 proton in the nucleus Hydrogen atoms and only hydrogen atoms have 1 proton in the nucleus Helium atoms and only helium atoms have 2 protons in the nucleus Helium atoms and only helium atoms have 2 protons in the nucleus

14. Proton Practice Practice: How many protons are in each of the following elements? CarbonPotassiumNitrogenCalciumSilicon

15. Electrons Electrons give atoms their chemical properties Electrons give atoms their chemical properties In order for an atom to have a neutral charge, it must have the same number of electrons as it has protons. In order for an atom to have a neutral charge, it must have the same number of electrons as it has protons. Electrons = protons = atomic number Electrons = protons = atomic number

16. Electron Practice Practice: How many electrons are in each of the following elements? HeliumChlorineNitrogenAluminumBoron

17. Mass Number All atoms have a mass number All atoms have a mass number We can figure it out by rounding the Average Atomic Mass to the nearest whole number We can figure it out by rounding the Average Atomic Mass to the nearest whole number Mass number = protons + neutrons Mass number = protons + neutrons Neutrons = Mass number – protons Neutrons = Mass number – protons

18. Finding Neutrons Example: Carbon Example: Carbon Round the Average Atomic Mass to the nearest whole number: Round the Average Atomic Mass to the nearest whole number: 12.01 rounds to 12 How many protons in carbon? How many protons in carbon?6 Neutrons = Mass number – protons Neutrons = Mass number – protons Neutrons = 12 – 6 = 6

19. Neutron Practice Practice: How many neutrons are in each of the following elements? OxygenChlorineArgonAluminumPhosphorus

20. Atom Concept Map

21. First 25 Elements Activity

22. Isotopes Isotopes of an element have the same number of protons, but different numbers of neutrons. Isotopes of an element have the same number of protons, but different numbers of neutrons. There can be many isotopes of the same element. There can be many isotopes of the same element.