# Ms. Belcoure’s Mid-Term

 How many significant figures are there in 0.732 m.
 3
 Define matter
 Something with both mass and volume
 Is soil a homogeneous or heterogeneous mixture?
 heterogeneous
 How are mixtures separated?
 By using physical properties
 What physical property is being taken advantage of in the distillation process?
 boiling point
 What does the arrow in a chemical reaction signify?
 the direction the reaction is going in
 What is a qualitative observation?
 An observation without numbers.
 What is a quantitative observation?
 An observation with numbers. A measurement.
 What is an accurate measurement?
 A measurement that comes close to the true value.
 What is a precise measurement?
 A measurement that comes close to several previous measurements.
 Can a measurement be precise but not accurate?
 Yes
 When using scientific notation the exponent indicates how many times the coefficient must be multiplied by 10. Which way does the decimal point move if the exponent is negative?
 To the left.
 Which way will you move the decimal if the exponent is positive?
 To the right.
 What are included as significant figures when doing a scientific measurement?
 All the digits that are known precisely (There are usually lines for these.) plus one last digit that is estimated.
 How many significant figures are there in 7004 m.
 4
 How many significant figures are there in 0.0056 m.
 2
 How many significant figures are there in 700 m.
 One, unless the zeros are measured values.
 How many nanometers are in a meter?
 1,000,000,000
 Express the following answer in scientific notation with the correct number of significant figures. 7.8g + 34.15g + 19g =
 6.1 x 10^1 g
 Define density.
 Mass divided by Volume
 A 35.0 mL metal cube weighed 242.455g. What is its density? Answer with the correct number of significant figures.
 6.93 mL/g
 A substance is described as hard, is that a qualitative or quantitative description?
 Qualitative
 Each element on the periodic table has two numbers. What is the smaller number called?
 Atomic Number
 Each element on the periodic table has two numbers. What is the larger number called?
 Mass Number
 What does the Atomic Number tell us about subatomic particles?
 The number of protons equals the atomic number.
 How would you calculate the number of neutrons from the periodic table?
 Mass Number – Atomic Number = Number of Neutrons
 How much do electrons affect the Mass Number?
 They don’t, their mass is negligible.
 When is an atom an isotope?
 Elements with the same number of protons but a different number of neutrons.
 What is the atomic number of radium?
 88
 What is the mass number of radium-226?
 226
 Determine the number of neutrons in radium-226.
 138 neutrons (Subtract the atomic number from the mass number.)
 What are the horizontal rows on the periodic table called?
 periods
 How many valence electrons does a helium atom have?
 2
 Are these the questions that make up Ms. Belcoure’s final?
 No, but this is the content you need to know for that final.
 What are the vertical columns on the periodic table called?
 groups or families
 Are most elements metals or non-metals?
 metals
 Which blocks make-up the representative elements?
 s and p
 What makes the electron configurations unique in the representative elements?
 the outermost s and p sublevels are partially filled
 As we move across a period in the periodic table what subatomic particle is added?
 proton
 As we move across the periodic table one proton is added to each element. What other subatomic element must be added if the atom is to remain neutral?
 electron
 What is added as we move down a group?
 energy level
 Nitrogen’s electron configuration is 1s2 2s2 2p3. How many electrons are in the outermost sublevel of Phosphorus? (CLUE: Not energy level, sublevel.)
 3
 Which is a transition metal? sodium, iodine, nickel or uranium(Know why, these aren’t the ones on the test.)
 nickel
 Which is an inner transition metal? sodium, iodine, nickel or uranium(Know why, these aren’t the ones on the test.)
 uranium
 Of the three subatomic particles, the electron plays the greatest part in determining the physical and chemical properties of an element. What sublevel is being filled as we move, left to right, along the transition metals.
 d
 The arrangement of elements in the periodic table depends on physical and chemical properties. Therefore, there is a relationship between the electron configuration of an element and its position on the table. What sublevel is being filled as we move, left to right, along the inner transition metals.
 f
 Atomic radius increases as we move down a group. Why?
 Another energy level is filled which increases the size of the electron cloud.
 State the main premise of the law of conservation of mass.
 matter cannot be created or destroyed in a chemical reaction
 What subatomic particle is lost to form a cation?
 electron
 What force holds electrons to the atom?
 positive protons, electromagnetic
 Which has the largest radius, neutral calcium or its ion? (Know why, this isn’t the one on the test?)
 neutral calcium
 Metals are on which side of the stair-cased line?
 left
 What is electronegativity?
 an atom’s ability to attract electrons
 Which element has the highest electronegativity? Fe, Cl, B, Cs (Know why, these are not the one’s on the test.)
 Cl
 Which element would you expect to have the properties most like carbon? (Again, know why.)
 silicon
 What is most of the volume in any atom?
 empty space
 A nuclear particle that has about the same mass as a proton, but with no electrical charge, is called a(n)…
 neutron
 What is the nucleus, except a common isotope of hydrogen, made up of?
 tightly packed protons and neutrons
 An isotope of titanium consists of 22 protons, 22 electrons, and 25 neutrons. What is its mass number?
 47 (Again, the element on the test is not this one.)
 Isotopes are atoms of the same element that have different…
 number of neutrons
 Write the Lewis dot structure for potassium.
 there should be one dot (Be sure you can do all the representative elements)
 What is the name given to the electrons in the highest occupied energy level of an atom?
 valence electrons
 How are the noble gasses unique?
 the outermost s and p sublevels are completely filled
 The octet rule means atoms react to imitate __________.
 the electron configuration of a noble gas
 How does lithium obey the octet rule when reacting to form an ionic compound?
 it loses one electron
 What is calcium’s oxidation number?
 +2
 What ion does oxygen become when reacting with a metal?
 anion, -2
 Which kind of ion does neon become when reacting with a metal?
 Trick Question, none of the noble gasses form ions
 How many electrons must nitrogen gain to achieve a noble gas electron configuration?
 3
 How many electrons must barium give up to achieve a noble gas electron configuration?
 2
 What is bromine’s oxidation number?
 -1
 Will carbon and oxygen form an ionic compound?
 no
 Will lithium and oxygen form an ionic compound?
 yes
 What is a polyatomic ion?
 two or more atoms, covalently bonded with a charge
 What is a salt?
 an ionic compound
 What type of bond shares electrons?
 covalent
 What type of bond is formed between anions and cations?
 ionic
 What state are ionic compounds usually in at room temperature?
 solid
 Melting points are good indicators of bond strength. The higher the melting point of a compound the stronger the bond. The melting point of sodium chloride is relatively _____________.
 high
 An element’s chemical properties are determined by __________________.
 valence
 Which is the most reactive? Li, B, C, Ne
 Li
 What is the mass of aluminum-27 isotope?
 27
 Which electron configuration belongs to the element that is the most chemically reactive? 1s22s22p63s23p6, 1s22s22p5, 1s22s22p6, 1s2
 1s22s22p5
 Which group of elements is inert?
 noble gasses
 What will cause the element with the electron configuration 1s22s22p63s23p4 to have an octet configuration?
 gain 2 electrons
 Which of the following is NOT matter? atoms, ultraviolet radiation, air, the Sun
 What element has 5 protons and 6 neutrons?
 boron
 What is the branch of chemistry that focuses on carbon-containing chemicals called?
 organic chemistry
 What neutral atom has 88 electrons?
 Which is poured first when preparing an acid solution, acid or water?
 water,add acid to water slowly
 What element has an atomic number of 78?
 platinum
 How many significant figures are in the value 213 000 m/s
 3
 If you need to write 215 000 g in scientific notation, how many significant figures should be included.
 It has three significant figures
 Write 319 000 000 in scientific notation.
 3.19 x 10^8
 Round 12.655 cm to four significant figures.
 12.66 cm
 Which is a compound salt, air, or nickel?
 salt
 How many electrons does Osmium-190 have?
 76
 Which of the following is a homogeneous mixture, silicon, air, nickel?
 air
 How do you know a reaction is exothermic?
 it releases energy, usually in the form of heat
 Which of the following is an element salt, brass aluminum?
 aluminum
 Elements of the same group have the same number of ______________?
 valence electrons
 Most of the elements in groups 6A-8A are classified as ______________. ; Clue:noble gases are 8A, halogens are 7A
 nonmetals
 Is RbI ionic?
 yes
 Identify the period and group of the element that has the electron configuration [Ne]3s2 3p3.
 period 3, group 5A
 An element with the electron configuration 1s22s22p63s2 will ionize to a(n)…
 cation
 Is the following electron configuration stable or unstable, [Ar}4s^2 3d^10 4p^5
 unstable
 Is the following electron configuration a metal or a non-metal, [Ar}4s2 3d10 4p5
 non-metal
 What is the electron configuration for the element in group 4A and period 4 of the periodic table?
 [Ar]4s^2 3d^10 4p^2
 What should you use to measure volume?
 a graduated cylinder, or you could use a ruler and calculate the volume
 The trend in the atomic radii as you move doewn the group 1A elements is partially due to ____________.
 shielding by inner electrons
 Which is larger, Br or Br–.
 Br-
 What units are used to express volume?
 liters, milliliters or cm^3
 How many electrons does an atom generally need in its outer level to be the most stable?
 8
 An element with the electron configuration 1s2 2s2 2p6 3s2 will ionize to a(n);
 cation
 Elements in the same group have similar chemical properties because…
 they have the same number of valence electrons.
 What electrons are involved in the formation of a covalent bond?
 shared valence electrons
 Describe the relationship between boron and silicon.
 They have a diagonal relationship.
 What is the value of all conversion factors?
 1
 Name three elements found most frequently in living organisms?
 carbon, nitrogen, and oxygen
 How many moles are 1.2 x 1024 molecules of CH4?
 2.0 moles CH4
 Is the following electron configuration a nobel gas, ns^2 np^6? (where n equals one through seven)
 yes
 How many formula units are in 2.3 moles of NaCl?
 1.4 x 10^24 formula units NaCl
 How many outer d electrons are there in an ion that has achieved a pseudo-noble gas configuration?
 ten
 In a chemical equation where are catalysts written?
 above the arrow
 What is the formula of calcium phosphate?
 Ca3(PO4)2
 What are the diatomic seven?
 hydrogen, nitrogen, oxygen, florine, chlorine, bromine, iodine
 How many electrons are shared in a double bond?
 four
 When balancing a chemical reaction there is only one type of number that can be changed. What do we call them?
 coefficients
 A mole of potassium chloride (KCl) contains 6.02 x 1023 ____________.
 formula units
 The SI unit of molar mass is the ______.
 grams/mole
 How many moles of oxygen atoms do 1.5 moles of CO2 contain?
 3.0 mol
 Which has the smallest molar mass: CO, CO2, H2O, H2O2 ?
 H2O
 One mole of silicon(Si) has a mass of 28.086 g, and one mole of carbon has a mass of 12.011 g. What is the mass of one mole of silicon carbide (SiC)?
 40.097g
 The correct Lewis structure for a molecule of the compound C2H2 contains how many double bonds?
 1
 Methane (CH4) contains 75% carbon. What percentage of methane is hydrogen?
 25%
 Write the chemical formula for sodium bromide dihydrate.
 NaBr*2H2O
 Is bromine stable or unstable?
 stable, because it is neutral
 What are units of concentration?
 moles
 Stoichiometry is bases on what law?
 conservation of mass
 What is molar mass?
 The sum of the masses of all the atoms in a compound
 Where do you look to find mole ratios for a reaction?
 balanced chemical reaction
 In the decomposition reaction AB into substances A and B, what is the number of mole ratios?
 6
 1.73 moles of an Ideal Gas has a pressure of 365.38 torr, at 272.6 Kelvin. Using the constant 62.36 L(torr/mol K), what is its volume?
 80.5L
 What will an acid produce in water?
 H+ or H3O+, hydronium ions
 Find the mass in grams of 2.23 x 1024 atoms of nitrogen.
 51.8 g N
 Is bromine and metal or nonmetal?
 nonmetal
 What is the most important industrial chemical in the world?
 H2SO4, sufuric acid
 List the 3 most studied types of radiation from most massive to least massive.
 alpha, beta, gamma
 What is the majority of an atom’s volume occupied by?
 nothing, empty space
 Define exothermic reactions.
 Exothermic reactions release energy into the environment.
 In a fusion reaction would you expect the product(s) to have more or less mass than the reactant(s)?
 more
 Write the name for Ca(OH)2?
 calcium hydroxide
 In a fission reaction would you expect the product(s) to have more or less mass than the reactant(s)?
 less
 What is the electron configuration of the element in group 4A and period 4 of the periodic table?
 [Ar]4s23d104p2
 What type of radioactive decay is not a particle?
 gamma
 Which family of elements are inert?
 noble gases
 Are half lives the same for different isotopes?
 No, different isotopes have different half lives.
 What element is [Ar]4s23d104p5 ?
 Br
 What happens to the size of atoms as you go down a group?
 The size increases
 What is the product when magnesium is burned in oxygen?
 MgO
 What would be the correct coefficients in the chemical equation of Mg reacting with oxygen?
 2,1,2
 What will a base produce in water?
 OH-, hydroxide ions
 Give two reasons the size of an atom increases as you move down a group.
 1. Each has a new principal energy level. 2. shielding by inner electrons
 Name 2 things that are not matter?
 energy, forces, light, emotions
 Is air matter? Why?
 Yes, because it has volume and mass.
 Is H2CO3 an acid or a base? Why?
 acid: because it will donate a proton
 Why do chemists do titrations?
 to determine the concentration of an unknown
 What is potassiums oxidation number?
 1+
 Is NaF ionic or covalent?
 ionic
 Which is most stable: [Ne]3s23p5 [Ne]3s23p64s23d5 [He]2s22p3 [Ne]3s23p6
 [Ne]3s23p6
 Is SO2 ionic or covalent?
 covalent
 How does a covalent bond differ from an ionic bond?
 Ionic bonds result from the transfer of electrons. Covalent bonds result from the sharing of electrons.
 Elements in the same group have the same number of ________________.
 valence electrons
 Are groups 6A through 8A be in the metals or nonmetals side of the periodic table?
 non-metals
 Identify the period and group of the element that has the electron configuration [Ne]3s23p3.
 period 3, group 5A