Organization of The Periodic Table

1. Organization of The Periodic Table

2. Nucleus • Center of the atom. • Makes majority of the atom’s mass. • Made of Protons and Neutrons. Nucleus

3. Protons • Part of the nucleus • Have positive (+) charge

4. Neutrons • Part of the nucleus • Have neutral charge

5. Electrons • Orbit around the nucleus • Have negative (-) charge

6. Atomic Number • Definition: the number of protons in the nucleus • Tells us the identity of the element. Every element is defined by the number of protons in its nucleus

7. Isotopes • Atoms with the same number of protons but different numbers on neutrons • Example: Carbon So you can change the number of neutrons and the element still maintains its identity

8. Questions • 1) What particles make up an atom? • 2) What are the charges on these particles? • 3) What particles make up the nucleus?

9. Questions • 1) What is Oxygen’s atomic number? • 2) How many protons does Oxygen have? • 3) If I have 4 protons what element am I? • 4) If I have 4 neutrons what element am I?

10. Reading the Periodic Table Mass

11. Atomic Mass • Definition: the ~ mass of one atom of an element • Tells us how much one atom weighs in atomic mass units. Mass

12. Organization of The Periodic Table Group/Family Period Ordered by atomic mass. Columns arranged to form groups with similar properties

13. Assessment • Which element has the greatest atomic mass? • Lithium • Sodium • Potassium • Rubidium

14. Reactivity • The ease and speed with which an element combines, or reacts, with other elements or compounds Pure sodium reacts explosively with air

15. Groups/families of elements have similar reactivity Group 1: metals that react violently with water Group 18: Gases that barely react at all

16. Atoms have neutral charge • # of Protons (+) = # of Electrons (-) = 0 charge • Example: Hydrogen • How many electrons does C have?

17. Take home message • The properties of an element can be predicted from its location on the Periodic Table

18. Metals, Metalloids, and Nonmetals

19. Metals • Shiny • Solids (at room temp) • Malleable – can be hammered flat • Ductile – can be pulled into wire • High Conductivity – ability to transfer heat or electricity to another object

20. Reactivity of Metals Low High Metals will usually lose electrons when they react with other elements

21. Nonmetals • Opposite of properties of metals • Not shiny • Poor conductors • Mostly gases (at room temperature) • Solids are brittle Sulfur

22. Reactivity of Nonmetals Low Low High Nonmetals will usually gain or share electrons when they react with other elements

23. Some Important Nonmetals • Carbon – important element for making up living organisms • Noble Gases – group 18 – very nonreactive. Have full outer shells.

24. Metalloids • Inbetween metals and nonmetals • Solids (at room temp) • brittle and hard • Semiconductors – can conduct electricity under some conditions but not others. • very important for computer chips • Most common example – Silicon – in sand and glass

25. Assessment • The atomic number is the number of • valence electrons. • neutrons. • protons in the nucleus. • electrons in the nucleus.

26. Assessment • The periodic table is a chart of the elements that shows the repeating pattern of their • energies. • properties. • element symbols. • names.

27. Assessment • Which piece of information cannot be found in a square on the periodic table? • Atomic mass. • Chemical symbol. • Atomic number. • Number of neutrons.

28. Assessment • Which side of the periodic table contains most of the nonmetals? • Left side. • Right side. • Middle.

29. Assessment • Which is not a property of nonmetals? • Brittle. • Nonmalleable. • High conductivity. • Most are gases at room temperature