Atomic Structure

Item 13: Part B What is the atomic mass of the element that consists of the following isotopes in the indicated natural abundances? Isotope Isotopic mass (amu) Relative abundance (%) 1 57.93 67.76 2 59.93 26.16 3 60.93 1.25 4 61.93 3.66 5 63.93 1.16

(57.93*0.6776)+(59.93*0.2616)+(60.93*0.0125)+(61.93*0.0366)+(63.93*0.0116) = 58.7amu

Item 11: Part D Which element does X represent in the following expression: ⁴¹₂₀X?

Ca

Item 14: Part C Rank the molecules (listed below along with the abundances of the individual atoms) by the height of their peaks in the mass spectrum for BrCl.

Highest Peak 79Br35Cl Abundance: 38.41% 81Br35Cl Abundance: 37.36% 79Br37Cl Abundance:12.28% 81Br37Cl Abundance: 11.95% Lowest Peak

Item 4: Part C A solution of ammonia and water contains 4.50×10²⁵ water molecules and 5.20×10²⁴ ammonia molecules. How many total hydrogen atoms are in this solution?

H₂O: 2(4.50x10²⁵)=9.00x10²⁵ NH₃: 3(5.20x10²⁴)=1.56x10²⁵ 9.00x10²⁵+1.56x10²⁵=1.06x10²⁶ H atoms

Item 20: Part A Suppose that one of Millikan's oil drops has a charge of −4.8×10−19 C. How many excess electrons does the drop contain?

N=3 electrons

Item 10: Part A What are the atomic number and mass number for the carbon isotope with seven neutrons?

Z, A= 6,13

Item 3: Part A Consider the following description. A brief statement that summarizes past observations and predicts future ones. This describes ______. a scientific law a hypothesis an experiment a theory

a scientific law

Item 16: Part B Find the number of atoms in a copper rod with a length l of 9.85 cm and a radius r of 1.05 cm . The density of copper is 8.96 g/cm3 . (The volume of a cylinder is V=πr2l.)

amount = 2.90×10²⁴ atoms of Cu

Item 18: Part A What is the chemical formula for quartz?

formula for quartz: SiO₂

Item 16: Part A A titanium cube contains 2.86×10²³ atoms. What is the edge length l of the cube? The density of titanium is 4.50 g/cm³ . (The volume of a cube is V=l3.)

l = 1.72 cm

Item 2: Part C A blood sample contains several different types of cells, each of which contains different combinations of specific ions and molecules. The cells are suspended in water, and the water also contains many molecules and ions. Which term or terms could be used to describe this sample of blood? Check all that apply. mixture heterogeneous mixture homogenous mixture solution pure chemical substance compound element

mixture heterogeneous mixture

Item 2: Part A A sample of tap water consists of water, fluoride ions, calcium ions, and several other dissolved ions. The ions are evenly distributed throughout the water. Which term or terms could be used to describe this sample of tap water? Check all that apply. mixture heterogeneous mixture homogenous mixture solution pure chemical substance compound element

mixture homogenous mixture solution

Item 9: Part B The atomic number of carbon is 6. What is the mass number of a carbon atom with 5 neutrons?

n+p=mass 6+5= 11

Item 18: Part B How many oxygen atoms are in 3.30 g of quartz?

number of O atoms = 6.62×10²²

Item 9: Part A Which subatomic particle(s) are found in the nucleus of the atom?

protons, neutrons

Item 2: Part D A gas turbine is filled with pure methane for use as a fuel. Which term or terms could be used to describe the contents of this gas turbine? Check all that apply. mixture heterogeneous mixture homogenous mixture solution pure chemical substance compound element

pure chemical substance compound

Item 2: Part B A sample of pure aluminum that is free of impurities is used to prepare a beverage can. Which term or terms could be used to describe this sample of aluminum? Check all that apply mixture heterogeneous mixture homogenous mixture solution pure chemical substance compound element

pure chemical substance element

Item 9: Part E Give the nuclear symbol for the isotope of argon for which A=38?

³⁸₁₈Ar

Item 10: Part B What is the symbol for the carbon isotope with seven neutrons?

¹³₆C

Item 8: Part A The element magnesium has significantly fewer protons and neutrons than gold. If you were to use Mg in place of Au in the Rutherford experiment, how would you predict the results from the experiment to change? There would be no change. The center spot would be smaller and the alpha particle scattering would be reduced. The center spot would be smaller and the alpha particle scattering would be the same. The center spot would be larger and there would be more alpha particle scattering.

The center spot would be smaller and the alpha particle scattering would be reduced.

Item 7: Part A Which of the following statements is correct? The particles that comprise cathode rays are about 100 times less massive than a hydrogen atom. Cathode rays are attracted to the cathode in a cathode ray tube. The charge on the oil drops in Millikan's experiment were all multiples of −1.60 × 10−19 C. Positive and negative charges repel one another.

The charge on the oil drops in Millikan's experiment were all multiples of −1.60 × 10−19 C.

Item 8: Part B How do the results of the Rutherford experiment suggest that the nucleus is positively charged? The large center spot is caused by small alpha particle deflections when they pass by a positively charged nucleus. The Rutherford experiment can't tell us the nucleus is positively charged. Because the center spot disappears when gold is placed in front of the alpha particle beam. Because some of the alpha particles are scattered at wide angles.

The large center spot is caused by small alpha particle deflections when they pass by a positively charged nucleus.

Item 9: Part D An atom of iron is represented by ⁵⁷₂₆Fe. How many neutrons are in the nucleus of this atom?

57-26=31

Item 4: Part B How many atoms of hydrogen (H) are present in 200 molecules of ammonia (NH₃)?

600

Item 11: Part B The ion N3− has ? protons and ?electrons.

7 protons, 10 electrons

Item 19: Part D Based on your answer in Part B, how many neutrons are in this amount of 13C?

7(9.26x10²²) = 6.48×10²³ neutrons

Item 11: Part C What isotope has 18 protons and 22 neutrons?

Argon-40

Item 21: Part A A naturally occurring sample of an element contains only two isotopes. The first isotope has a mass of 68.9255 amu and a natural abundance of 60.11 %. The second isotope has a mass of 70.9247 amu. Find the atomic mass of the element.

(68.9255*0.6011)+(70.9247*0.3989) = 69.72 amu

Item 13: Part A What is the atomic mass of a hypothetical element that consists of the following isotopes in the indicated natural abundances? Isotope Isotopic mass (amu) Relative abundance (%) 1 85.9 10.7 2 89.9 12.1 3 93.9 77.2

(85.9*0.107)+(89.9*0.121)+(93.9*0.772)= 92.6 amu

Item 19: Part A How many moles of atoms are in 2.00 g of 13C?

0.154 mol 13C

Item 19: Part B Based on your answer in Part A, calculate the number of atoms in this amount of 13C?

0.154(6.022*10²³)= 9.26×10²² 13C atoms

Item 1: Part A Complete the sentences outlining the main points of this video 1. Matter is composed of _____. 2. The structure of those ____ determines the ____ of matter.

1. Matter is composed of particles. 2. The structure of those particles determines the properties of matter.

Item 5: Part A There are two different compounds of sulfur and fluorine. In SF6, the mass of fluorine per gram of sulfur is 3.55 g F/g S. In the other compound, SFX, the mass of fluorine per gram of sulfur is 1.18 g F/g S. What is the value of X for the second compound?

1.18*3=3.55 F6 to Fx = 3:1 X=2

Item 15: Part A How many carbon atoms are there in a 1.3-carat diamond? Diamonds are a form of pure carbon. (1 carat = 0.20 g.)

1.3 carat*(0.2g/1carat)*(1mol C/ 12.01g)*(6.022*10²³carbon atoms/1mol C) = 1.3*10²² carbon atoms

Item 17: Part A Which statement is FALSE? One mole of beryllium (Be) contains the same number of atoms as 22.99 g of sodium. 11.495 g of sodium contains 6.022×1023 atoms. One mole of calcium (Ca) weighs about as much as two moles of neon (Ne). There are about 2.007×1023 atoms in 9.0 g Al.

11.495 g of sodium contains 6.022×10²³ atoms.

Item 14: Part B What are the masses of the four different BrCl molecules?

117.882,115.885,115.884,113.887 amu

Item 6: Part B The law of conservation of mass states that mass is neither created nor destroyed during a chemical reaction. This can be gleaned from the third postulate in Dalton's series. Magnesium oxide decomposes into magnesium and oxygen. If 16.12 g of magnesium oxide decomposes to form 9.72 g of magnesium, what mass of oxygen gas is also released in the reaction?

16.12-6.72=6.40g

Item 4: Part A What is the ratio of hydrogen atoms (H) to oxygen atoms (O) in 2 L of water? Enter the simplest whole number ratio in order of hydrogen to oxygen, respectively.

2, 1

Item 15: Part B Calculate the mass of 2.25×1022 tungsten atoms.

2.25*10²²atomsW*(1mol W/ 6.022x10²³atoms W)*(183.84g/1mol W) = 6.87 g

Item 9: Part C An atom has a mass number of 24 and 13 neutrons. What is the atomic number of this atom?

24-13=11

Item 11: Part A Specify the number of protons, neutrons, and electrons in the neutral atom bromine-80

35, 45, 35 protons, neutrons, electrons

Item 14:Part A How many peaks will be present in a mass spectrum for BrCl?

4 The four different molecules are 81Br37Cl, 81Br35Cl, 79Br37Cl, and 79Br35Cl.

Item 12: Part A Consider a hypothetical element X that consists of two isotopes one with a mass of 41.99998 amu and the other with a mass of 44.99987 amu. Their percent abundances are 33.3333% and 66.6667%, respectively. Without doing an actual calculation, the mass closest to the atomic mass of X is ______.

44.0 amu

Item 6: Part A Which of the following reactions is possible according to Dalton's atomic theory? N2→O2 N2+O2→2NO CO2→NO2 H2O→H2S

N₂+O₂→2NO

Item 5: Part B Samples of three different compounds were analyzed and the masses of each element were determined. Compound Mass N Mass O A 5.6 3.2 B 3.5 8.0 C 1.4 4.0 If you were John Dalton and had never heard of a mole, which of the following would you think were possible sets of formulas for the compounds A, B, and C, respectively? Check all that apply. NO2, NO8, NO10 NO, NO2, NO4 NO4, NO10, NO5 N2O, N2O4, N2O5

N₂O, N₂O₄, N₂O₅