1. ATOMS AND THE PERIODIC TABLE chapter three

2. ATOMIC THEORY - history 4 TH CENTURY B.C. Matter is made of tiny particles called ATOMS. John DALTON ELEMENTS are made of particles called atoms. ATOMS of the same elements are alike. ATOMS form molecules. EARLY 1900’s (1913) ELECTRONS orbit like planets in the solar system. MID 1900’s (after 1925) Modern theory 3.1 Atomic Structure

3. ATOMIC THEORY - STRUCTURE MODEL OF THE ATOM ELECTRON - NUCLEUS PROTON + NEUTRON (NEUTRAL) ENERGY LEVELS 3.1 Atomic Structure

4. ATOMIC STRUCTURE ELECTRON LOCATION Electrons are found in energy levels of an atom. Electrons occupy the lowest energy level available. 3.1 Atomic Structure

5. Energy Levels are like ladder rungs… GAINING ENERGY 3.1 Atomic Structure

6. Energy Levels 3.1 Atomic Structure

7. ORBITALS – where the electrons are located within an energy level. S orbital (Like a sphere) may contain up to 2 electrons first energy level is an s orbital 3.1 Atomic Structure

8. P orbital (Like a dumbbell) may contain up to 2 electrons second energy level may contain an s orbital and up to 3 p orbitals 3.1 Atomic Structure

9. Orbitals 3.1 Atomic Structure

10. Valence electrons are located in the outermost energy level of an atom. They determine the chemical properties of an element. 3.1 Atomic Structure

11. 3.2 A TOUR OF THE PERIODIC TABLE Properties of elements change in a regular pattern that the table helps to describe. Periods – Horizontal Rows Groups(families) – Vertical Columns

12. Traditional Periodic Table Los Alamos National Laboratory's Chemistry Division Presents a Periodic Table of the Elements 3.2 Guided Tour of Periodic Table

13. The number of protons in an atom determines an element’s location on the table. 3.2 Guided Tour of Periodic Table

14. 6 C Carbon 12.001 ATOMIC NUMBER SYMBOL NAME MASS PROTONS (and ELECTRONS too) PROTONS + NEUTRONS MASS # Elements On the Periodic Table 3.2 Guided Tour of Periodic Table

15. 1 1 18001 PROTONS AND NEUTRONS HAVE EQUAL MASS. ELECTRONS ARE TINY – 1800 EQUAL ONE PROTON. 3.2 Guided Tour of Periodic Table

16. MASS 35 ATOMIC NUMBER 17 Cl protons _?_electrons _?_ neutrons _?_ 3.2 Guided Tour of Periodic Table

17. MASS 35 ATOMIC NUMBER 17 Cl protons 17electrons 17 neutrons 35-17 = 18 3.2 Guided Tour of Periodic Table

18. IONS are atoms that have lost or gained an electron. ELECTRON GAINED = NEGATIVE CHARGE (-) ELECTRON LOST = POSITIVE CHARGE (+) 3.2 Guided Tour of Periodic Table

19. Na+ Cl Electron transfer 3.2 Guided Tour of Periodic Table

20. TWO KINDS OF IONS: A (+) CHARGED ION IS A Cation. A (-) CHARGED ION IS AN Anion. EXAMPLES: LITHIUM FLUORIDE 3.2 Guided Tour of Periodic Table

21. The atoms of an element always have the same number of protons. BUT….. The atoms of an element may have different numbers of neutrons. This is an ISOTOPE! Two carbon ISOTOPES: CARBON 12 = 6 protons and 6 neutrons CARBON 14 = 6 protons and 8 neutrons 3.2 Guided Tour of Periodic Table

22. The AVERAGE MASS of an ATOM Why is the mass number not an even number? –Atoms of the same element exist with different numbers of neutrons. –This makes the mass of different atoms of the same element different. –The average mass is a weighted number so that more common isotopes have a greater affect on the average than rare isotopes. What is an amu? –It is an “atomic mass unit”. –An amu is equivalent to the mass of 1/12 of a carbon-12 atom. 3.2 Guided Tour of Periodic Table

23. 3.3 FAMILIES OF ELEMENTS: HAVE THE SAME VALENCE NUMBER. HAVE SIMILAR CHEMICAL AND PHYSICAL PROPERTIES. A COLUMN OF ELEMENTS IS A FAMILY.

24. TWO MAJOR DIVISIONS METALSNONMETALS 3.3 Families of Elements

25. GROUP ONE: ALKALI METALS VERY REACTIVE ONE VALENCE ELECTRON 3.3 Families of Elements

26. GROUP TWO: ALKALINE EARTH METALS TWO VALENCE ELECTRONS 3.3 Families of Elements

27. GROUP 3-12: TRANSITION METALS MANY COMMON METALS NOT AS REACTIVE AS OTHER METALS 3.3 Families of Elements

28. GROUP 17: HALOGENS VERY REACTIVE FORM SALTS WITH ALKALI METALS 7 VALANCE ELECTRONS 3.3 Families of Elements

29. GROUP 18: NOBLE GASES INERT / UNREACTIVE EIGHT VALENCE ELECTRONS 3.3 Families of Elements

30. SYNTHETIC ELEMENTS They are man-made and radioactive. They include all elements above #92, plus #43 and #61. 3.3 Families of Elements

31. SEMICONDUCTORS (METALOIDS) The elements that are between the metals and nonmetals are known as: SEMICONDUCTORS (METALOIDS) They may exhibit metallic and nonmetallic properties. B Si GeAs 3.3 Families of Elements

32. 3.4 USING MOLES TO COUNT ATOMS Some counting units: –Reams of paper –Dozens of eggs –Atomic mass units of protons and neutrons –Moles of atoms A mole is the SI unit that describes the amount of a substance. Avogadro’s constant is the number of particles in one mole which = 6.022 x10 23 molar mass is the mass in grams of one mol of a substance…it is equal to the average atomic number of an atom.

33. Vocabulary Parts of an atom History Element families Using the periodic table Metal vs. nonmetal Chapter 3 Studying for the Test