17

Chapter 17

Properities of Atoms and the Periodic Table

Section One: __Vocab__

Atom: smallest piece of matter that still retains the property of the element Nucleus: small, positively charged center of an atom containing protons and neutrons and is surrounded by a cloud containing electrons Protons: particles with an electrical charge of 1+ Neutrons: neutral particles that don not have an electrical charge Electrons: particles with an electric charge of 1- Quarks: make up protons and neurons and are smaller particles Electron Cloud: area around the nucleus of an atom where its electrons are most likely found

Section Assessment: 1. List some chemical symbols: A: Carbon C, Aluminum Al, Hydrogen H, Oxygen O, and Sodium Na 2. Identify the names, charges, and locations of three kinds of particles that make up an atom. A: Proton + charge, Neutron neutral charge, are both located in the nucleus of an atom. The electrons - charge are located around the nucleus in a cloudlike form. 3. Identify the smallest particle of matter. How were they discovered? A: the smallest particle of matter is the quark. The quark was discovered by accelerating charged particles to great speeds and smashing them into protons. 4. Describe the electric cloud model of an atom. A: This model shows how the electrons form a cloud much like sokes on a moving bicycle wheel, they are kind of a blur. 5. Elpain how a rotating fan might be used to model the atom. Explain how the fan is unlike an atom. A: A fan may be used to model an atom becasue the fan blades form somthing similar to a electron cloud. But there is really nothing to model the neutrons and protons. Also the fan is flatlike where an atom is more 3-D sphere-like. 6. 1.6726 x 10 -24 9.1093 x 10 -28 How many times larger is the mass of the proton compared to the mass of the electron? A: 7. What is the difference between the mass of an electron and the mass of an electron? A: 1,836 ??

Reading Check: Protons and neutrons are located inside the neuclus and the protons are located on the outside. Models can simplify science because they make things easy to see and study.

Picture Questions: A long tunnel is needed to accelerate it to a higher speed.

Section Two: __Vocab__

Atomic Number: is equal to the number of protons in an atom Mass Number: of an atom is the sum of the number of protons and the number of neutrons in the nucleus of an atom Isotopes: atoms of the same element that have different numbers of neutrons Average Atomic Mass: weighted-average mass of the mixture of its isotopes Reading Check: Most of the mass is located in the nucleus Carbon 146 neutrons

Reading Questions: These two items are isotypes becasue they are the same element but have a different number of neutrons.

Section Assessment: 1. Identify the mass number and the atomic number of a chorine atom that has 17 protons and 18 neutrons. A: mass number: 35 atomic number: 17 2. Explain how the isotypes of an element are alike and how they are different. A: They are still the same element but have different mass numbers and number of neutrons. 3. Explain why the atomic mass of an element is an average mass. A: It has to due with isotopes which have different neutron numbers meaning it must be an average of the two. 4. Explain how you would calculate the number of neutrons in potassium-40. A: You wold take the mass number minus the atomic number. 5. Why does this indicate that most chrinr atoms contain 18 neutons? A: Becuase that is the avarge of the the two (36/2) 6. If a hydrogen atom has two neutrons and one protons what is its mass number? A: 3 add the two together 7. Use the information in Table 2 to find the mass in kilograms of each subatomic particle. A: Proton 16,726 x 10 -24 Neutron 16,749 x10 -24 Electron 91,093 x 10 -28 (Move each decimal over 4 places because kilograms to grams is 4 spaces.)

Applying Science:

1. 48,800 Million years 36,600 Million Years 2. 1,115million years Lead

Section 3- The Periodic Table Vocabulary Periodic Table- elements are arranged by increasing atomic number and by change in physical and chemical properties Group- families (vertical columns in the periodic table) Electron Dot Diagram- uses the symbol of the element and dots to represent the electrons in the outer energy level Periods- horizontal rows of elements on the periodic table __ Reading Check: __ Aligned properties and atom masses of the elements, masses gradually increasing from left to right. Mass decreases from left to right, Atomic number always increases from left to right 2 electrons Since all members of a group on the periodic table have the same number of electrons in their out energy level Metals and one nonmetal __ Picture Questions __ They show the ultimate energy level possible __ Section 3 Assessment __ Use the periodic table to find the name, atomic number, and average atomic mass of the following elements: N, Ca, Kr, and W. A:Nitrogen, 7, 14.007 Calcium, 20, 40.078 Krypton, 36, 83.798 Tungsten, 74, 183.84 List the period and group in which each of these elements is found: nitrogen, sodium, iodine, and mercury. A: Nitrogen: 2, 7 Sodium: 3, 11 Iodine: 5, 53 Mercury: 6, 80 Classify each of these elements as metal, a nonmetal, or a metalloid and give the full name of each: K, Si, Ba, and S. A: Potassium, nonmetal Silicon, metalloid Barium, metal Sulfur, nonmetal The Mendeleev and Mosely periodic charts have gaps for the as-then-undiscovered elements. Why do you think the chart used by Mosely was more accurate at predicting where new elements would be placed? A: Because it was based on elements increasing atomic numbers instead of an arrangement based on atomic masses.