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PS 1422 Lecture Notes Chemical Formulas and Equations: The number of atoms in a molecule of ammonium sulfide, (NH4)2S, is 11
and the formula of mercury (II) nitrate is Hg (NO3)2. The formula for sodium bicarbonate is Na H CO3. The Law of composition means different pure samples of a compound always contain the
same elements in the same proportion by mass. We change the coefficients in order to balance the equation and not violate the Law of conservation of matter. The name of the compound Cu2O is copper (I)
oxide. The particle that is formed when an atom gains an electron is called an ion. A molecule always contains two or more atoms. The smallest unit of a compound that still maintains the chemical properties of the
compound is a molecule. The atomic masses of the elements are related to the mass of 12000 grams of carbon-12. One mole of atomic He contains 6.02x1023 atoms. If a nail is magnetized, this is an example of
a physical change. But when milk sours this is an example of a chemical change. What is the total number of known elements? Buckyball is an example of allotrope not an example of a compound of carbon. It is known that
most abundant element in the earth's crust is oxygen. To balance the equation C2H6 + O2 ---> CO2 + H2O the correct coefficients are (2,7,4,6).
To balance the equation K Cl O3 ---> K Cl + O2, the correct coefficients are (2,2,3). The covalence of carbon in covalent compounds is 4, which are 4 single bonds. A double bond between two
atoms is stronger than a single bond between the same two atoms. Write the formulas for water, hydrochloric acid, Lead (II) chloride and sodium chloride. What is the number of sulfur atoms in Al2(SO4
)3. The answer is 3. How many atoms are present in this formula? The total number of atoms in table sugar is 45 (verify it). The science that deals with the composition, structure, properties,
and reactions of matter is called chemistry. It was Berzelius who first developed the modern symbol notation for elements. In 1661, Boyle developed a definition of element that made the concept subject to
laboratory investigation. When the atoms of two or more elements react chemically, they usually join together to form molecules. The periodic table is most easily understood in terms of the electron configurations of
the elements. What is the electron configuration of the potasium K? The horizontal rows of elements in the periodic table are called periods. The periodic law states that the properties of elements are periodic
functions of the atomic number. The formula mass of ammonium phosphate, (NH4 )3 PO4, is 149 u. ( verify it). Flammability is not a physical property of matter whereas density,
specific heat and boiling point are. A balanced chemical equation will have the same number of atoms of each element on each side. The type of reaction 2 Cu (NO3 )2 ---> 2 Cu O + 4 NO
2 + O2, is decomposition. The most important acid to industry is sulfuric acid, which is also used in a car battery. Some sample questions:
Electrons in the outermost shell are referred to as ________ electrons. a. orbital b. f shell c. s shell d. valence What is the balancing coefficient of Oxygen on the left of the equation.
P + O ---> P O5 a. 4 b. 3 c. 1 d. 5 The numbers needed to balance the equation Al + F ----> AlF3 are a. 1,3,2. b. 2,1,2. c. 4,3,2. d. 1,3,1.
When Calcium reacts with chlorine, the compound is a. CaCl b. Ca2Cl c. Ca2Cl2 d. CaCl2 There are four different atoms in the compound, AlPO4
a. True b. False A chemical reaction is represented by a chemical equation. a. True b. False Pure water contains only H2O moleculs. a. True b. False
In the balanced chemical reaction, PbCl2 + H2S--->PbS + HCl How many units of HCl must be produced? a. Two b. One c. Four d. Many e. None of these
Which of the following is not an element? a. Na b. H2O c. Fe d. C Brass is an example of a. an element b. a compound c. a mixture
Milk sours. This is an example of a. a chemical change b. a physical change The total number of known elements is a. 92 b. 109 c. 114 d. 100 The most abundant element in the Universe is
a. oxygen b. silicon c. helium d. hydrogen The most abundant element in the earth's crust is a. helium b. hydrogen c. oxygen d. iron The formula of sodium bicarbonate is: a. NaBiCO3
c. NaHCO3 b. Na(CO3)2
d. Na(HCO3)2 One mole of H2O molecules contains a. 3.01x1023
molecules c. 6.02x1023 hydrogen atoms b. 6.02x1023 atoms d. 1.8x1024
atoms Different pure samples of a compound always contain the same elements in the same proportion by mass. This is known as the a. law of conservation of mass b. law of Dalton
c. law of conservation of compounds d. law of constant composition What is the mass of 3.01x1022 moles of sulfur?
a. 16 g c. 1.6 g
b. 0.16 g d. 9.6x1023 g
We would conclude that, based upon the Law of Conservation of Matter, a. atoms are conserved in a reaction b. molecules are conserved in a reaction c. coefficients are conserved in a reaction
d. all of the above In order to balance a chemical equation and not violate the Law of Conservation of Matter, we change the
a. subscripts c. both the subscripts and coefficients
b. coefficients d. products Name the compound Cu2O.
a. dicopper oxide c. copper (II) oxide b. cupric (II) oxide d. copper (I) oxide
How would you name the acid HNO3? a. nitric acid c. hydronitric acid
b. nitrous acid d. pernitric acid The particle that is formed when an atom gains an electron is called
a. a molecule c. a compound
b. an ion d. a mole A molecule always contains two or more
a. different elements c. atoms b. compounds d. grams
The smallest unit of a compound that still maintains the chemical properties of the compound is
a. a molecule c. an element
b. an atom d. a mole The atomic masses of the elements a. are known absolutely
b. are measured by weighing each atom c. are related to the mass of 12,000 grams of carbon-12 d. can always be counted by observing protons and neutrons Which is not matter? a. charcoal b. air c. heat
d. electrons A nonchemical combination of two or more substances in varying proportions is called a. a mixture. b. a compound. c. a molecule. d. an ion.
A substance composed of two or more elements chemically combined in a definite, fixed proportion by mass is a. a mixture. b. an ion. c. a molecule. d. a compound.
In which shell would the valence electrons of sodium be found? a. 1 b. 2 c. 3 d. 4 What is group number and period number of lithium with Z = 3? a. 1,1 b. 2,2 c. 3,3 d. 1,2
The periodic law states that the properties of elements are periodic functions of the atomic a. number b. mass c. shell d. radius Which type of reaction is 4 Sb + 3 O2
--> Sb4O6? a. direct combination b. decomposition c. single-replacement d. double replacement Which type of recaction is 2 Al + 3 H2SO4--> Al
2(SO4)3 + 3 H2 ? a. direct cobination b. decomposition c. single-replacement d. double-replacement Which is the most important acid to industry?
a. hydrochloric acid b. sulfuric acid c. phosphoric acid d. nitric acid The formula mass of aspirin, C9H8O4, is a. 324 u. b. 182 u. c. 326 u. d. 180 u
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