Atomic Structure Picture What do you know about atomic structure already? 1
How did we get the information for our modern atomic structure? 10 minute movie http://www.bozemanscience.com/history of the atom 2
SmartBoard Response Log in Number Write your log in number TWO places for example: inside cover of workbook AND inside cover of your journal Breakdown of what your number means...so which controller you should take: 3
1 What is the part of the atom with the most mass called? A neutron B nucleus C electron cloud D proton 4
2 What subatomic particle has a charge that is negative? 5
Modern Atomic Theory 1. All matter is composed of atoms. ATOM: Basic unit of an element that retains all the element's chemical properties. ELEMENT: A substance that contains one type of atom. For example: 2. An atom is not the smallest particle of matter, but it is the smallest that retains the chemical properties of an element. 3. Atoms of an element are identical in size, average mass, and chemical properties. THUS, every element is unique in the above characteristics. 4. Atoms cannot be created or destroyed, but they can be combined or rearranged through a chemical reaction. MOLECULE: A combination of two or more atoms. Examples: COMPOUND: A combination of two or more atoms of different elements in a precise proportion by mass. Examples: 6
3 True or False. Elements are made up of atoms. True False 7
4 Which of the following could be called a molecule? A H2O (water) B NaCl (table salt) C CaCl2 (calcium chloride) D O2 (oxygen) E All of the above 8
5 Which of the following would NOT be a compound? A H2O (water) B NaCl (table salt) C CaCl2 (calcium chloride) D O2 (oxygen) E All of the above are compounds. 9
Subatomic Particles Every atom is built of the same 3 subatomic particles, just in different quantities. Protons The number of protons in an atom determines the identity and the chemical properties of an atom. The number of protons = the atomic number Neutrons The number of neutrons can vary and will affect the mass, but not the identity, of an atom. MASS NUMBER: Number of protons plus neutrons in the nucleus of an isotope. ISOTOPE: Atom of an element which has a different mass number. Example: Carbon 11, Carbon 12, Carbon 13, Carbon 14, Carbon 15 http://www.chemicalelements.com/show/mass.html One more way to write an isotope = symbolic isotope Superscript = mass number (P+N) Subscript = atomic number (P) Beside the elemental symbol Examples: 10
Electrons Electrically neutral atom means the number of protons is equal to the number of electrons. IONS: Number of protons and electrons is not equal. Ions with a negative charge (anions) = more electrons than protons (addition of electrons) Ions with a positive charge (cations) = less electrons than protons (loss of electrons) Structurally Electrons move in high speed "shells/clouds", which is most of the volume, but none of the mass. 11
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Model Isotopes 1. Calculate percent abundance of each group of pennies (isotopes). 2. Determine mass contribution to the overall atomic mass. 2a. Add the mass contributions together to obtain the atomic mass of the 'penny'. 3. Would the atomic mass be different if you received another bag with a different mix of pennies? 4. Why did we measure 10 pennies at once instead of just one? 13
How would you calculate your grade in this class if Skyward did not do it for you? 1. Percents in each category. 2. Change those percents to decimals. 3. Points in each category. 4. Put the equation together and solve for your percent in the class. 14
4: Calculating Average Atomic Mass WS 15
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Mass number on periodic table with decimal = Atomic mass Atomic mass on the periodic table a weighted average of the different naturally occurring isotopes of an element. How to calculate this? Atomic mass = (percent of isotope 1) x (isotope 1 mass) + (percent of isotope 2) x (isotope 2 mass) +... Example problem: 1. Magnesium has three naturally occurring isotopes. 78.70% of Magnesium atoms exist as Magnesium 24 (23.9850 g/mol), 10.03% exist as Magnesium 25 (24.9858 g/mol) and 11.17% exist as Magnesium 26 (25.9826 g/ mol). What is the average atomic mass of Magnesium? 2. Calculate the average atomic mass of this unknown element with two known isotopes: Isotope 1: Mass 34.97 Frequency 75.77% Isotope 2: Mass 36.97 Frequency 24.23% Then, use your periodic table to name the unknown element. 17
Real world application FBI Agent Mrs. Goodnight! Hunt for Counterfeit Moolah! 18
Density Notes Density is an important property of matter. Density can be used to identify substances. DENSITY = quantity of matter in a given unit of volume. Math relationship is: Density = mass/volume or D = M/V Units? could be g/ml or g/cm 3 Finding volume of a regular shaped solid: Volume = length x width x height (measure in cm to get unit of cm 3 ) Irregular shaped objects? Use water displacement! Units = ml 19
6 If Lithium has a +1 charge, how many electrons are present? 20
7 If Phosphorous has a 3 charge, how many electrons are present? 21
8 If Barium has a charge of +4, how many electrons are present? 22
9 If Magnesium has a charge of +2, how many protons are present? 23
10 What is the mass of an electron? A 0 B 1 C very little compared to neutrons and protons D both A and C E 24
11 What would be your average quiz grade if your percents were 80, 77, 64, and 92? (round to the whole number and do not put the percent sign) 25
12 Calculate the average atomic mass of Candium. Isotope one = mass of 111.88 g and frequency of 39%. Isotope two = mass of 109.40 g and frequency of 30%. Isotope three = mass of 74.46 g and frequency of 31%. A 43.633 amu B 23.083 amu C 32.820 amu D 99.536 amu 26
13 Find the volume of an object with a density of 0.76 g/ml and a mass of 106.4 grams. (Just the whole number with no units) 27
14 A student measures the mass of an object as 135.80 g. Calculate the percent error in the measurement, given that the accepted value for the mass is 137.23 g. (Whole number with no units) 28
15 Calculate the height of a rectangular pan if the length is 27.0 cm, width is 14.55 cm, and the volume is 3653.505 cm^3. (Only one number after the decimal point and no units) 29
16 Find the mass of an object with a density of 4.5 g/cm^3 and a volume of 12 cm^3. (whole number with no units) 30
17 Calculate the density of an object that has a mass of 39.26 g and when I place it in 20 ml of water, the water level raises to 37.1 ml. (one place after the decimal and no units) 31
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