1. Unit 4: Atoms

2. I. Dimitri Mendeleev a.A Russian Chemist b.Created the first periodic table in 1869 i. In 1869, 63 elements had been discovered 1. Most were metals, a few were gases and only two were liquids. ii. Mendeleev is the one who found that there are sets of patterns within the different elements.

3. I. Dimitri Mendeleev c. Mendeleev’s Work i. He noticed that some elements had similar physical properties 1. Such As: Silver and copper are both shiny metals ii. He thought that these were clues to other hidden patterns iii. To help find the patterns Mendeleev documented three things 1. The elements Melting Point 2. The elements Density 3. The elements Color iv. He then added Atomic Mass. 1. Atomic Mass is the average mass of all isotopes of the element

4. I. Dimitri Mendeleev d. Mendeleev’s Periodic Table i. He arranged the cards going from lowest Atomic Mass to highest Atomic Mass. ii. When arranging them in this fashion, he noticed that patterns repeated regularly 1. Example: Lithium (Li), Sodium (Na), and Potassium (K) all react when put in water. iii. He finally created his Periodic Table in 1869 1. Mendeleev’s Periodic Table was incomplete 2. He left empty spaces for elements he thought would have that given atomic mass but had not been found yet

5. II. The Periodic Table Today a.Periodic mean: Regular or repeating pattern i. Why do you think it is named this? ii. Atoms: We must first understand Atom Structure to better understand the Periodic Table 1. Atoms: Everything is made up of Atoms a. Three Parts: i. Protons - positively charged (in nucleus) ii. Neutrons – no charge (in nucleus) iii. Electrons – negatively charged (in outside cloud)

6. II. The Periodic Table Today b. Protons: These are what give us the Atomic Number i. Atomic Number is the number of protons in the nucleus ii. Every atom of the same element will have the same number of Protons and therefore the same Atomic Number. c. Neutrons: No Charge and are held in the nucleus i. Protons and Neutrons added together give the atom its atomic mass d. Electrons: Move around the outside of the nucleus i. Have a negative charge ii. Electrons and Protons are oppositely charged and are therefore attracted to each other 1. This attraction is what keeps the atom together

7. III. Reading the Periodic Table a.Atomic Number: this is the amount of protons in the atom b.Atomic Mass: average number of protons and neutrons found in all isotopes of an atom c.Chemical Symbol: a one or two letter abbreviation d.Label the different parts of this element from the periodic table

8. III. Reading the Periodic Table e. Period i. These are rows of different elements 1. The properties of these elements change in a pattern 2. Metals are listed on the left 3. Nonmetals are listed on the right 4. Metalloids are listed in the middle 5. There are 7 periods

9. III. Reading the Periodic Table e. Groups i. These are also called families ii. This is a group of elements that have the same properties 1. Example Group 1 are all metals that react violently with water

10. Warm Up #6 Be sure to write the question and answer in complete sentences 1.Describe the differences between the periodic table that we use today and the periodic table Mendeleev made. 2.Name and describe the three different parts of the atom. 3.Describe a Period on the periodic table in as much detail as you can. 4.Describe a Group on the periodic table in as much detail as you can. 5.As I go across my periodic table, how are metals, nonmetals, and metalloids arranged? 6.How many protons does Silicon have? How many does Lead have? 7.What is the Chemical Symbol for Krypton and Xenon?

11. IV. Metals a. Properties of Metals i. Good conductors of electric current and heat 1. Conductor: material through which electrical or thermal energy can pass through ii. Metals tend to be shiny and bendable. iii. Metals make up most of the periodic table b. Physical Properties i. Luster: shiny and reflective ii. Malleable: can be hammered or pressed into different shapes without breaking or cracking iii. Ductile: can be pulled or drawn into long wires iv. Thermal Conductivity: the ability to transfer heat v. Electrical Conductivity: the ability to carry an electrical current

12. IV. Metals c. Chemical Properties i. Reactivity: the ability (ease and speed) in which an element combines with other substances ii. Metals normally react by losing an electron to another atom 1. Na (____________________) reacts easily with water 2. Au (_____________) and Pt (____________________________) do not react as easily with other substances 3. This reactivity has to do with how much the atom “wants” to give up its electrons iii. Metals also go through corrosion 1. This is the deterioration of a metal because of chemical reactions in the environment

13. IV. Metals i. Six different groups of metals ii. Alkali Metals 1. Group 1 from Lithium (Li) to Francium (Fr) 2. These are the most reactive metals on the periodic table 3. These elements are never found alone in the environment. a. In other words, they are always found combined to at least one other element 4. These metals have low densities and low melting points

14. IV. Metals iii. Alkaline Earth Metals 1. Group 2 2. These metals are still very reactive just not as much as alkali metals 3. These are more dense and have higher melting points 4. These metals are never found alone in nature a. They are always found combined to another substance iv. Transition metals 1. Group 3-12 2. Most are hard and shiny a. Mercury however is a liquid at 25 degrees Celsius 3. These have higher densities and melting points 4. They are good conductors of electricity and heat 5. Less reactive than groups 1-2

15. IV. Metals v. Metals in Mixed Groups 1. Group 13-16 2. Only some of these elements are metals vi. Lanthanides and Actinides 1. These are found in the two rows under the periodic table 2. Top row Lanthanides. a. also known as rare earth elements 3. Bottom Row Actinides a. Most of these are not found in nature but are made in laboratories

16. IV. Metals e. Transuranium Elements i. Elements following uranium are made by nuclear reactions ii. To make elements 95 and above they used a particle accelerator iii. The newer elements do not have permanent names or numbers as they are still testing and experimenting with them.

17. Warm Up #8 Rewrite each question and answer in complete sentences. 1.What are Transuranium Elements? 2.How does Reactivity change as you move across the periodic table (within the metals) 3.How do densities and melting points change as you move across the periodic table (within the metals) 4.What are the 4 different properties of metals? 5.Describe in more detail two of those four properties.

18. V. Nonmetals and Metalloids a.Many of the elements that make up our earth are nonmetals b.Nonmetals have a wide variety of properties c.Nonmetals lack the physical properties of metals d.These are all found on the right side of the periodic table i. Except for Hydrogen e. Physical Properties of nonmetals i. They are poor conductors of heat and electricity ii. Solid nonmetals are dull and brittle 1. If you were to hit this with a hammer most would break or crumble into a powder

19. V. Nonmetals and Metalloids iii. Nonmetals tend to have a lower density than metals iv. Most are gases at room temperature 1. Exceptions. a. Carbon, Phosphorus, Sulfur and Iodine are solids b. Bromine is the only nonmetal that is a liquid f. Chemical Properties of nonmetals i. Nonmetals gain or share electrons when around other atoms 1. Example: When Sodium and Chlorine (Na and Cl) react with each other, Sodium gives away an electron and Chlorine takes the electron from Sodium

20. V. Nonmetals and Metalloids 2. Example : When two nonmetals form a compound, the nonmetals share their electrons g. The Nonmetal Families i. The Carbon Family 1. Group 14 2. In this group, carbon is the only nonmetal 3. Carbon is important because it is the building blocks of most everything in life (Proteins, DNA, carbohydrates)

21. V. Nonmetals and Metalloids ii. The Nitrogen Family 1. Group 15 2. Contains two nonmetals a. Nitrogen and Phosphorus 3. Nitrogen makes up 78% of the earths atmosphere 4. Nitrogen will be found in nature as a Diatomic Molecule a. This is an atom that is made up of two atoms b. Therefore, Nitrogen is made up of two Nitrogen Atoms bonded together (N 2 ) 5. Phosphorus is very reactive and will not be found alone in nature

22. V. Nonmetals and Metalloids iii. The Oxygen family 1. Group 16 2. Contains three nonmetals a. Oxygen, sulfur, and selenium 3. Oxygen is a Diatomic Molecule 4. Oxygen can react with almost every other element

23. V. Nonmetals and Metalloids iv. The Halogen family 1. Group 17 2. These are salt forming elements 3. Fluorine is the most reactive element a. It reacts with almost every known substance, even water v. The Noble Gases 1. Group 18 2. These elements do not normally form compounds 3. They do not gain, share, or lose electrons 4. These, therefore, are very nonreactive

24. V. Nonmetals and Metalloids vi. Hydrogen 1. Simplest and most common atom 2. Rarely found as pure form on earth. vii. Metalloids 1. Mixed properties of metals and nonmetals 2. Solid at room temperature 3. Somewhat reactive and are known as semiconductors

25. VI. Atom Structure a. Atoms have all their protons and neutrons in their nucleus. i. Protons will always be the same for each atom of the same element ii. Amount of Neutrons can change, these are called Isotopes 1. This is how we get the Atomic Mass a. The average of all the different forms of the same element 2. Naming Isotopes: Name of Element-number of neutrons + number of protons 3. Example: Carbon (blue-protons; red-neutrons)

26. VI. Atom Structure b. The electrons are in the outside cloud i. These electrons are moving at a rapid rate, therefore, when we take a picture of an atom it looks like a cloud

27. VI. Atom Structure c. Electron Orbitals (these can also be called shells) i. We start counting from the inside out ii. The first orbital only holds 2 electrons iii. The second, third, (ect) orbital holds up to 8 electrons iv. Example 1: Carbon 1. Total Number of Electrons 6 v. Example 2: Chlorine 1. Total Number of Electrons 17 vi. Example 3: Sodium 1. Total Number of Electrons 11

28. VI. Atom Structure d. These outer shell electrons are called valence electrons e. Atoms want to give or take electrons to get a full outer shell f. The number of valence electrons is what “decides” whether or not an atom will give away electrons or take electrons

29. VI. Atom Structure g. Periodic Table and Valence Electrons i. There is a pattern between the periods and the number of valence electrons ii. Each period begins with an element with 1 valence electron and ends with an element that has 8 valence electrons iii. The groups also follow a pattern with valence electrons 1. Group 1 has 1 valence electron 2. Group 2 has 2 valence electrons 3. Group 13 has 3 valence electrons 4. Group 14 has 4 valence electrons 5. Group 15 has 5 valence electrons 6. Group 16 has 6 valence electrons 7. Group 17 has 7 valence electrons 8. Group 18 has 8 valence electrons a. Except for Helium which only has 2 valence electrons

30. VI. Atom Structure h. Element Dot Diagram i. Each dot stand for a valence electron ii. Example: Carbon iii. Example : Oxygen iv. Example: Argon v. Why are dot diagrams helpful?

31. VII. Atoms and Bonding a. An elements chemistry or ability to bond is related to the amount of valence electrons it has to offer other elements b. Elements are stable when they have 8 valence electrons i. Exception: Hydrogen is stable with 2 electrons; as well as helium c. When atoms bond they either share their electrons or they transfer their electrons d. Bonding by Position on Periodic Table i. Nobel Gases: Do not react easily, some do not react at all ii. Metals: React by giving up extra valence electrons 1. Except for Lithium, when a metal in Group 1 gives up an electron, they get a full shell of 8 electrons iii. Nonmetals: These become stable when they gain or share electrons from another atom 1. Nonmetals usually bond with metals 2. When bonding with nonmetals or metalloids they share electrons

32. VII. Atoms and Bonding iv. Metalloids: These either lose or share electrons v. Hydrogen: Shares their electrons when bonding with other nonmetals vi. Fill in the following chart Group NameNumber of Valence Electrons Reactivity (High/low) Alkali Metals Halogens Noble Gases

33. Democritus (460 B.C-370 B.C)

34. Dalton’s Model (Early 1800’s)

35. Thomson’s Model (1906)

36. Rutherford’s Model (1910)

37. Electron Cloud Model (Today)