Atoms

Slide 1: 

Unit D Chapter 1Atomic Structure and the Periodic TableBy Jerry Mullins

Principle 1 : 

Principle 1 Matter is made of particles too small to see A substance’s atomic structure determines its physical and chemical properties.

Section 1.1Atoms are the smallest form of elements : 

Section 1.1Atoms are the smallest form of elements All matter is made of atoms. Each element is made of a different atom. Atoms form ions

Objectives : 

Objectives Students will: Define key vocabulary; Recognize where atoms of some common elements are found and how they are named; Describe atomic structure and how that structure determines an element’s identity; Explain how ion form from atoms; Model the relative masses of atomic particles in an experiment

Warm-up : 

Warm-up Via transparency 4 Match the definitions with the terms

Vocabulary : 

Vocabulary Matter Atom Proton Neutron Nucleus Electron Atomic number Atomic mass number Isotope Ion (positive/negative)

Explore Lab : 

Explore Lab “The Size of Atoms” Question: How small can you cut paper? Materials: Strip of paper (30cm) Scissors Procedure: Cut strip of paper in half. Cut one of these halves in half. Continue cutting one piece of paper in half as many times as you can. What do you think: How many cuts were you able to make? Do you think you could keep cutting the paper forever? Why or why not?

Slide 8: 

Composition of Matter Matter - Everything in universe is composed of matter Matter is anything that occupies space or has mass Mass – quantity of matter an object has Weight – pull of gravity on an object

Slide 9: 

Elements Pure substances that cannot be broken down chemically into simpler kinds of matter More than 100 elements (92 naturally occurring)

Slide 10: 

90% of the mass of an organism is composed of 4 elements (oxygen, carbon, hydrogen and nitrogen) Each element unique chemical symbol Consists of 1-2 letters First letter is always capitalized Elements

Element Symbols : 

Element Symbols Each element is represented on the periodic table by a symbol. Atomic Number (number of protons) Atomic Mass (total number of protons and neutrons) (average mass of all isotopes)

Slide 12: 

Atoms The simplest particle of an element that retains all the properties of that element Properties of atoms determine the structure and properties of the matter they compose Our understanding of the structure of atoms based on scientific models not observation

Slide 13: 

The Nucleus Central core Consists of positive charged protons and neutral neutrons Positively charged Contains most of the mass of the atom

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The Protons All atoms of a given element have the same number of protons Number of protons called the atomic number Number of protons balanced by an equal number of negatively charged electrons

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The Neutrons The number varies slightly among atoms of the same element (producing isotopes discussed later)

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The Electrons Negatively charged high energy particles with little mass Travel at very high speeds at various distances (energy levels) from the nucleus

Slide 17: 

Electrons in the same energy level are approximately the same distance from the nucleus Outer energy levels have more energy than inner levels Each level holds only a certain number of electrons The Electrons

Energy Levels : 

Energy Levels Electrons occur in discrete energy levels around the nucleus of an atom. These energy levels are often represented as circles. Within an energy level, electrons can be found in orbitals. The first, or innermost, energy level can hold two electrons. The second and third energy levels can each hold eight.

Valence Electrons : 

Valence Electrons Valence Electrons are defined as… the electrons in the outermost energy level that are involved in chemical bonding. Example: An atom of chlorine has 7 valence electrons. Octet Rule – To become more stable, atoms will gain, lose, or share valence electrons in order to obtain an octet (8 valence electrons).

Lewis Dot Diagrams : 

Lewis Dot Diagrams Valence electrons are the most important in forming chemical bonds. Lewis dot diagrams show only the valence electrons as dots surrounding the element symbol. 7 valence electrons

What are Isotopes? : 

What are Isotopes? While some atoms of certain element’s always have the same number of protons, they may not always have the same number of neutrons, so not all atoms of an element have the same atomic mass number Isotopes are atoms of the same element that have a different number of neutrons Some elements have many isotopes while other elements have few

Slide 22: 

Determining Isotopes You can find the number of neutrons in a particular isotope by subtracting the atomic number from the atomic mass number Atomic number (-) Atomic mass = # neutrons Example: Cholorine-35 indicates the isotope of chlorine that has 18 neutrons. Chlorine-37 has 20 neutrons. Every atom of a given element always has the same atomic number because it has the same number of protons. Remember the atomic mass number varies depending on the number of neutrons

Slide 23: 

Atoms form Ions Some atoms become stable by losing or gaining electrons Atoms that lose electrons are called positive ions. Why? Because there are more protons than electrons causing an overall net positive charge

Slide 24: 

Atoms that gain electrons are called negative ions Because positive and negative electrical charges attract each other ionic bonds form Atoms form Ions

Investigative Lab : 

Investigative Lab “Masses of Atomic Particles” Question: How can you model the relative masses of atomic particles? Materials: Balance Large paper clip Other items Procedure: Use a paper clip to represent the mass of an electron. Determine its mass. Find a substance in the classroom (sand, clay, water) from which you could make a model representing the mass of a proton or neutron. The mass of a proton or neutron is about 2000 times the mass of an electron. Measure out the substance until you have enough of it to make you model. What do you think: What substance did you use to make your model? What was the model’s mass? What do you conclude about the masses of atomic particles?

Connecting Science : 

Connecting Science Identify chemical elements in the human body and the roles they play Work in lab group and discuss PE/TE p 16

Section 1.2Elements make up the Periodic Table : 

Section 1.2Elements make up the Periodic Table Elements can be organized by similarities. The periodic table organizes the atoms of the elements by properties and atomic number

Objectives : 

Objectives Students will: Define key vocabulary; Identify how the properties of elements are shown by the periodic table Complete group presentation on “knowing the element”; Identify Dmitri Mendeleev and his contribution to the periodic table; Describe how Mendeleev’s periodic table was organized; and Describe how today’s periodic table is organized.

Warm-up : 

Warm-up Transparency 4 (overhead) Correct any statement(s) that are not true

Vocabulary : 

Vocabulary Atomic mass Periodic table Group Period

Explore Lab : 

Explore Lab “Similarities and Differences of Objects” Question: How can different objects be organized? Materials: Buttons or other objects Procedure: Within you group, organize the buttons into three or more groups. Compare your team’s organization of the buttons with another team’s organization. What do you think: What characteristics did you use to organize the buttons? In what other ways could you have organized the buttons?

The Periodic Table : 

The Periodic Table The layout of the periodic table is determined by the electron configurations of the elements. We call it the periodic table because it shows a periodic, or repeating, pattern of properties of the elements.

Early Periodic Table : 

Early Periodic Table 1800’s scientist proposed system to organize the elements based on their properties. However, none of them worked well. 1860’s Dmitri Mendeleev organized the elements based on their physical and chemical properties Arranged elements on a chart in rows showing similar chemical properties so that atomic masses increased as one moved down each vertical column 1869 Mendeleev produced the first know Periodic Table

Today’s Period Table : 

Today’s Period Table Modern table on PE 20-21 Different from Mendeleev’s Elements of similar properties are found in columns, not rows. Elements are not arranged by atomic mass but by atomic number

Reading the Periodic Table : 

Reading the Periodic Table Each square gives particular information about the atoms of an element Number at top is the atomic number, (number of protons in nucleus); Chemical symbol is abbreviated. May contain one or two letters. Elements not yet named are designated by three-letter symbols Name of element is written below symbol Number below the name is the average atomic mass of all the isotopes of the elements

More on Reading Periodic Table : 

More on Reading Periodic Table Color of the chemical symbol indicates the physical state White=gas Blue=liquid Black=solid Background color of the square determines: Yellow=metal Purple=metalloid Green=nonmetal

Periods : 

Periods A period is a row on the periodic table. As you go from left to right across a period, there is a regular, or periodic, change in properties. With the start of each new period, a similar pattern begins again. Atomic size decreases from left to right across the period Everyday Analogy During a class period at school, you have roll call, collection of homework, lecture, practice problems, and assignments. When that ‘period’ is over you go to another class ‘period’ and the same general pattern starts over, even though it’s not exactly the same.

Groups : 

Groups A group is a column on the periodic table. Elements within a group have similar chemical properties. Because of these similarities, they are also called chemical families. Atomic size increases as you go down the group Everyday Analogy A group on the periodic table is like a family. Members of a family share many characteristics, even though each member has a unique identity. The Noble Gases are in the last group on the table. Just as “nobility” (kings and queens) don’t interact with “regular people,” these elements don’t react easily with other elements.

Investigative Lab : 

Investigative Lab “Modeling Atomic Masses” PE/TE 24-25 See handout

Section 1.3The periodic table is a map of the elements : 

Section 1.3The periodic table is a map of the elements The periodic table has distinct regions. Most elements are metals. Nonmetals and metalloids have a wide range of properties. Some atoms can change their identity

Objectives : 

Objectives Students will: Define key vocabulary; Classify elements as metals, nonmetals, and metalloids. Identify different groups of elements. Describe radioactive elements. Model half-life in an experiment

Warm-Up : 

Warm-Up Transparency 5 Look for the elements below in the periodic table on PE pp 21-21. Write how each pair of elements are related

Vocabulary : 

Vocabulary Reactive Metal Nonmetal Metalloid Radioactivity Half-life

Explore Lab : 

Explore Lab “Visual/Analytical Lab: Where on the Periodic Table are you?” Question: How are elements different? Materials: Lamp with light Aluminum Copper penny Procedure: find the element on your periodic table and note their location Draw the element diagram What do you think: Are the atoms of each element located in a different part of the periodic table? Which part of the period table are they located in? metal, nonmetal, or metalloid What other elements are near these?

Periodic Table Represents a Map : 

Periodic Table Represents a Map Just as a country’s location on the globe gives you information about its climate, an atom’s position on the periodic table has three main regions

Three Regions of the Period Table : 

Three Regions of the Period Table Metals on the left Nonmetals (except hydrogen) on the right Metalloids found in between these two Some periodic table indicate these regions by colors Green=nonmetal Purple=metalloid Yellow=Metal

Reactive : 

Reactive Position in the table also indicates how reactive an element is Reactive: indicates how likely an element is to undergo a chemical change Most elements are somewhat reactive and combine with other materials Group 1 & 17 are the MOST reactive Group 18 are the LEAST reactive

Most Elements are Metals : 

Most Elements are Metals In general: metals are elements that conduct electricity and heat well and have a shiny appearance. Can be shaped easily by pounding, bending, or being drawn into a long wire (except mercury!!!!) Mercury 80 (Hg) is liquid, metals are solids at room temperature.

Reactive Metals : 

Reactive Metals Group 1: Alkali Metals: (columns up/down) MOST REACTIVE Very reactive Sodium 11 (Na+) and potassium 19 (K+) often stored in oil to keep them away from air. If not, they will react rapidly with air and water The ions of these metals Na+ and K+ are important in life for the proper functioning of living cells.

Reactive Metals : 

Reactive Metals Group 2: Alkaline Earth Metals: (columns up/down) Less reactive than alkali metal Still most reactive then other metals Ca+ 20(calcium) essential to diet. Stored in bones and teeth Mg+ 12 (magnesium) is light. Often combined with other metal to product lightweight material such as airplane frames

Transition Metals : 

Transition Metals Groups 3-12: Transition Metals (columns up/down) Some of the earliest know elements such a copper 29 (Cu), gold 79 (Au), silver 47 (Ag), and iron 26 (Fe) Generally less reactive than other metals Today dimes, quarter made of copper (Cu). Nickels and pennies made of zinc30 (Zn) with a coating of copper Transition Metal ions found in food Important to industry: Iron 26 (Fe) is a main part of steel Most electric wires are copper, also water pipes tungsten 74 (W) used as a filament in light bulbs

Alloys : 

Alloys Combination of two or more metals Can be stronger Brass is an alloy of copper 29 (Cu) and zinc 30 (Zn) Jewelry is often made of an alloy of silver 47 (Ag) and copper 29 (Cu) (stronger than pure silver)

Rare Earth Elements : 

Rare Earth Elements Elements in the top row of the two rows of metals that are usually shown outside the main body of the periodic table

Nonmetals : 

Nonmetals Nonmetals: Elements located on the right side of the metalloids (zigzag line) on the periodic table. The properties of nonmetals tend to vary more from one another. Many are gases at room temperature Bromine 35 (Br) however is a liquid at room temperature General: Dull surfaces Cannot be shaped by hammering or drawing into wires Generally poor conductors of heat and electrical current

Nonmetals : 

Nonmetals Main components of air that you breathe are the nonmetal elements Nitrogen 7 (N) and Oxygen 8 (O2) Nitrogen 7 (N) Fairly unreactive Oxygen 8 (O2) Reacts easily to form compounds with many other elements Burning and rusting are two familiar types of reactions (rxn) related to

Nonmetals : 

Nonmetals Carbon 6 (C) Compounds containing C are essential to all living organisms Two forms or C: Graphite, which is soft, slippery black material (pencils) Diamond, hardest known crystal on earth WV coals mines Sulfur 16 (S) Bright yellow powder Mined from deposits of the pure element

Summation: Metals vs. Nonmetals : 

Summation: Metals vs. Nonmetals

Metalloids : 

Metalloids Lie on either side of the zigzag line separating metal from nonmetals 7 elements are Metalloids Germanium 32 (Ge); Antimony 51 (Sb) are located on the left side of the zigzag line Baron 5 (B); Silicon 14 (Si); Arsenic 33 (As); Tellurium 52 (Te); and Astatine 85 (At) located on the right side of the zigzag line Are all solid at room temperature have properties that are intermediate between the metals and nonmetals.

Metalloids : 

Metalloids Most common metalloid is Silicon 14 (Si) Second most common atoms found in Earth’s crust Metalloids often make up the semiconductors found in electronic devices Semiconductors are special material that conduct electricity under some conditions and not under others Silicon 14 (Si); Gallium 31 (Ga); and germanium 32 (Ge) most common material used in semiconductors in computer chips

Halogens : 

Halogens Group 17 (column up/down) MOST REACTIVE Greek meaning: Forming Salts Very reactive nonmetals that form compounds called SALTS with many metals Often used to kill harmful microorganisms (antibiotics) Chlorine 16 (Cl) used in drinking water to prevent growth of algae in swimming pools Iodine 53 (I) solutions used in medical facilities to kill germs on skin

Nobel Gases (Inert Gases) : 

Nobel Gases (Inert Gases) Group 18 (column up/down) least reactive Almost never react with other elements Argon 18(Ar) Makes about 1% of our atmosphere Nobel gases used often in colorful lighting Made by passing an electric current through tubes filled with either neon 10 (Ne), krypton 36 (Kr), xenon 54 (Xe), or argon 18 (Ar) gas Argon 18 (Ar) also found in tungsten 74 (W) filament light bulbs, because it will not react with the hot filament The Noble Gases are in the last group on the table. Just as “nobility” (kings and queens) don’t interact with “regular people,” these elements don’t react easily with other elements.

Radioactivity : 

Radioactivity Is a condition in which the number of protons in an atom’s nucleus changes and so changes the identity of an atom. Background: Each element has isotopes. The stability of a nucleus depends on the right balance of protons and neutrons. If there are too many neutrons, the nucleus may become unstable. When this happens, particles are produced from the nucleus of the atom to restore the balance. This change is accompanied by a release of energy

Radioactivity : 

Radioactivity Therefore: if the production of particles changes the number of protons, the atom is transformed into an atom of a different element. Discovery: 1900’s physicist Marie Curie named the process by with atoms produce energy and particle “Radioactivity” First to isolate polonium 84 (Po) and radium 88 (Ra)

Radioactivity : 

Radioactivity Understanding: an isotope is radioactive if the nucleus has too many or too few neutron. Most elements have radioactive isotopes, although these isotopes are rare fro small atoms. For the heaviest of elements—beyond Bismuth 83 (Bi)—all of the isotopes are radioactive

Geiger Counter : 

Geiger Counter Scientist study radioactivity with this device It detects particles from the breakup of the atomic nucleus as an audible click the more the audible clicks the more particles being produced

Radioactivity in Medicine : 

Radioactivity in Medicine Used in hospitals to diagnose and treat patients Some forms of radiation from nuclei used to destroy harmful tumors Another use of radiation is to monitor the activity of certain organs in the body Patient injected with radioactive isotope However, prolonged exposure to radiation linked to cancers and health problems

Radioactive Decay : 

Radioactive Decay Is the process in which the identity of atoms changes because the number of protons changes Over time, all of the atoms of a radioactive isotope will change into atoms of another element Decay occurs at a steady rate that is characteristic of the particular isotope Half-Life of the isotope: is the amount of time that it takes for one-half of the the atoms in a particular sample to decay

Half-Life of an Isotope : 

Half-Life of an Isotope Example If we had 1000 atoms of a radioactive isotope with a half-life of 1 year, 500 of the atoms would change into another element over the course of a year. In the next year, 250 more atoms would decay. Half-life is not affected by conditions such as temperature or pressure Half-life of isotopes can range from a small fraction of a second to many billions of years

Investigate Lab : 

Investigate Lab “Radioactivity” Question: How quickly can atoms change? Materials: 50 pennies Bag Graph paper Procedure: Put 50 pennies in a bag. The pennies represent 50 atoms Pour out the pennies Count the number of pennies that landed head side up. These represent atoms whose nuclei changed Refill the bag with only the pennies that landed tail side up Repeat steps 2-4 until all of the pennies have landed head side up. Each time you pour out the pennies counts as one turn Construct a graph with the number of atoms that changed on the y-axis and the number of turns on the x-axis. What do you think: After one turn, how many atoms had changed? Had not changed? In how many turns did all the atoms change? From looking at your graph, what can you conclude about the rate of radioactive change? Challenge: if you used a different number of pennies, would you results be different? In what way?

Unit D Chapter 1 Summation: : 

Unit D Chapter 1 Summation: Present group “knowing the elements” Present group Unit project Review exam Turn in group lab books and individual lab books Reteach if needed