Chem unit 3
average atomic mass calculation
(% abundance x mass of A-1) + (% abundance x mass of A-2)
Dalton's Atomic Theory
1) matter is made up of tiny, invisible particles called atoms 2) all atoms of a given element are identical to one another 3) Atoms of 2 or more different elements combine in simplest, whole-number ratios to form compounds. 4) Atoms are not detroyed in chemical reatctions. A chemical reaction only seperates, rearranges and recombines the atoms. 5) Atoms are the smallest things ever
If A has a atomic mass of 1 and B has a atomic mass of 2 what would the mass be for comound A2B4
10
Which one of daltons atomic theories is not true
2) when they talk about how all atoms have the same make up, but in reality all atoms have different number of portons ext 5) atoms are not the smalesst, protons, electrons and nuetrons are all smaller
1 mole of any gas = __ L
22.4
Define molar volume for a gas at STP.
22.4 L
If Irons atomic number is 26 how many protons, electrons and nuetrn does it have
26 protons, 26 neutrons, and 26 electrons
what is the ratio of CO2 to CO?
2:1, law of multiple proportions
What do the superscript and subscript represent in the notation ^40 (bottom) 19 K
40 is the atomic mass and 19 represents the atomic number
If A has a atomic mass of 1 and B has a atomic mass of 2 what would the mass be for comound AB2
5
what is avogadros number
6.02 x 10^23
1 mole of oxygen atoms = ___ O atoms
6.02x10^23
1 mole substance = how many particles
6.02x10^23
1 mole C-12 atom =
6.02x10^23 or 12g
Proton
A positively charged particle found in atomic nucleus.
Atomic mass unit
A relative mass of atom based on C-12
Electron
A small, negatively charged particles found in atoms.
isotopes
Atoms of the same element that have different numbers of neutrons
Isotopes
Atoms that have the same number of protons but different numbers of neutrons.
Millikan oil-drop experiment
Because of gravity the oil droplets fell between 2 charged plates. However when the voltage is applied and adjusted arrodingly, the downward gravataional force is cancelled by the upward drag of electric forces, the the charged oil dropplets stop falling and suspence.
discovering neutrons
Chadwick concluded that there was a new particle with a nuetral charge called a nuetron with a mass slighly greater than a proton.
discovering protons
Rutherford discovered that there was a tiny positive charge mass in the center of an atom, scientist did many expirements to conlcude that a proton has a positive chatge and its mass is 1 amu
Rutherfords gold foil scattering experiment
Rutherford shot alpha particles at a very thin sheet of gold, most of the particles passed straight thorugh but a few bounced back thus each atom contains a very small and dence nucelus in the center
Atomic mass
The average mass of an atom
What caused the deflection of the alpha particles in Rutherford's gold-foil expirement?
The deflection was because the particles it the nucleus.
In determining atomic mass units, the mass of _____ is used as the standard mass. a. C-12 atom. b. C-14 atom. c. H-1 atom. d. O-16 atom.
a
Isotopes of the same element have different ______. a. numbers of neutrons c. numbers of electrons b. numbers of protons d. atomic numbers
a
The abbreviation for atomic mass unit is _____. a. amu. b. mu. c. a. d. m.
a
The atomic number of oxygen is 8. It indicates that there are eight ______. a. protons in the nucleus of an oxygen atom. c. neutrons outside the oxygen atom's nucleus. b. oxygen nuclides. d. energy levels in the oxygen atom's nucleus.
a
Dalton's Atomic Model
atom is a solid sphere that cannot be divided up into smaller particles or pieces.
matter is made up of
atoms
A nuclear particle that has about the same mass as a proton, but with no electrical charge, is called a(n) _____. a. nuclei b. neutron. c. electron. d. isotope.
b
A sample of tin (atomic mass 118.69 amu) contains 3.01 ´ 1023 atoms. The mass of the sample is _____ a. 3.01 g. b. 59.3 g. c. 72.6 g. d. 11 g.
b
The nucleus of most atoms is composed of ______. a. tightly packed protons. c. tightly packed protons and neutrons. b. tightly packed neutrons. d. loosely connected protons and electrons.
c
The particles that are found in the nucleus of an atom are ____. a. neutrons and electrons c. protons and neutrons b. electrons only d. protons and electrons
c
The total number of protons and neutrons in the nucleus of an atom is its _____. a. atomic number. c. mass number. b. Avogadro constant. d. number of neutrons.
c
What is the molar mass of (NHmc058-1.jpg)mc058-2.jpgCOmc058-3.jpg? a. 144 g b. 138 g c. 96 g d. 78 g
c
what is the standard element to determine the mass of atom
carbon - 12
Thomson's experiments with cathode rays led to the discovery of the ______. a. proton. b. nucleus. c. neutron. d. electron.
d
What did Rutherford conclude about the structure of the atom? a. An atom is indivisible. c. An atom carries a positive charge. b. Electrons make up the center of an atom. d. An atom contains a small, dense, positively charged central region.
d
What is the number of moles of calcium atom in 9.03 ´ 1024 Ca atoms? a. 1.50 mol b. 9.03 mol c. 10.0 mol d. 15.0 mol
d
atomic mass unit
is defined as one-twelth of the mass of carbon - 12
Law of Conservation of Mass
mass is neither created or destroyed in a chemical reaction
Si - 28 what is 28 represent
mass number
another name for daltons atomic theory
solid sphere atomic model
gas molecules take up ________
space
mass number
the total number of protons and neutrons in the nucleus of an atom
Law of Multiple Proportions
when two elements combine with each other to form more than one comound, the masses of one element that combine with a fixed mass of teh second element are in the small whole number ratio.
Rutherford's Nuclear atomic model
1) an atoms consists of mostly empty space 2) electrosn spin around the nucelus 3) the nucelus is the center, very small dence, positively charged and contains most of the mass of the atom.
definition of a mole
The exact number of atoms in 12grams of C-12
Atomic number
The number of protons in the nucleus of an atom
Atomic Theory
The theory that all matter is composed of indivisible particles called atoms.
cathode ray tube
William Crooke created the CRT in 1875. It is a vaccum tube, when the power is tunred on, rays travle from the negative electrode to the positive electrode.
. What is the atomic number for aluminum? a. 13 b. 14 c. 26.98 d. 26.9815
a
2. The law of conservation of mass follows from the concept that _____. a. atoms are indivisible. c. matter is composed of atoms. b. atoms of different elements have different properties. d. atoms can be destroyed in chemical reactions.
a
Find the number of gaseous water molecules in 67.0 L a. 1.80 x 1024 b. 3.60 x 1024 c. 19.60 x 1024 d. None of the above
a
Find the number of oxygen molecules in 58.0 g. a. 1.09 x 1024 b. 5.80 x 1024 c. 2.18 x 1024 d. None of the above
a
Helium-4 and helium-3 are _____. a. isotopes. b. different elements. c. compounds. d. nuclei.
a
The mass of a neutron is _____. a. about the same as that of a proton. c. double that of a proton. b. about the same as that of an electron. d. double that of an electron.
a
The molar volume of any gas at STP is _____. a. 22.4 L b. 24.2 L c. 44.2 L d. 12 grams
a
The smallest particle of an element that retains the properties of that element is a(n) ____. a. atom b. electron c. proton d. neutron
a
law of definite proportions
a given chemical compound always contains its elemts in the same proportion by mass.
atomic number, # of protons , # electrons
all the same
Ag-109 has 62 neutrons. The Ag atom has ______. a. 40 electrons. b. 47 electrons. c. 53 electrons. d. 62 electrons.
b
All atoms of the same element have the same ______. a. number of neutrons c. mass numbers b. number of protons d. mass
b
As the atomic number increases, the number of electrons in an atom _____. a. decreases. c. remains the same. b. increases. d. is undetermined.
b
Dalton's atomic theory can be used to explain the law of conservation of mass because it stated that atoms ______. a. could not combine. c. all had the same mass. b. could not be created or destroyed. d. were invisible.
b
Find the volume in liters of 51.0 g of ammonia gas, NH3 a. 33.6 L b. 67.2 L c. 22.4 L d. None of the above
b
In oxides of nitrogen, such as N2O, NO, and NO2, atoms combine in small whole-number ratios. This evidence supports the law of _____. a. conservation of mass. c. definite composition. b. multiple proportions. d. mass action.
b
Nickel-60 (atomic number 28) has ______. a. 28 neutrons. b. 32 neutrons. c. 60 neutrons. d. 88 neutrons.
b
Protons have ______. a. negative charges. b. positive charge c. no charges. d. no mass.
b
The deflection of cathode rays in Thomson's experiments was evidence of the _____ nature of electrons. a. wave b. charged c. particle d. spinning
b
The mass of a sample of nickel (atomic mass 58.69 amu) is 11.74 g. It contains ______. a. 1.174 ´ 1023 atoms. c. 1.869 ´ 1023 atoms. b. 1.205 ´ 1023 atoms. d. 3.256 ´ 1023 atoms.
b
The number of atoms in 1 mol of carbon-12 is ______. a. 6.022 ´ 1022. b. 6.022 ´ 1023. c. 5.022 ´ 1022. d. 5.022 ´ 1023.
b
The rays produced in a cathode tube in early experiments were _____. a. unaffected by a magnetic field. c. found to carry a positive charge. b. deflected away from a magnet d. striking the cathode.
b
What does the number 84 in the name krypton-84 represent? a. the atomic number c. the sum of the protons and electrons b. the mass number d. twice the number of protons
b
What is the number of moles in 9.63 L of Hmc067-1.jpg gas at STP? a. 0.104 mol b. 0.430 mol c. 3.54 mol d. 14.7 mol
b
Which of the following is NOT a part of Dalton's atomic theory? a. All elements are composed of atoms. c. Atoms of the same element are identical. b. Atoms are always in motion. d. Atoms that combine do so in simple whole-number ratios.
b
Which of the following statements is NOT true? a. Protons have a positive charge. c. The nucleus of an atom is positively charged. b. Electrons are negatively charged and have a mass of 1 amu. d. Neutrons are located in the nucleus of an atom.
b
Why do chemists use relative masses of atoms compared to a reference atom rather than the actual masses of the atoms? a. The actual mass of an electron is very large compared to the actual mass of a proton. c. The number of subatomic particles in atoms of different elements varies. b. The actual masses of atoms are very small and difficult to work with. d. The actual masses of protons, electrons, and neutrons are not known.
b
atoms are the _______ ___________ of all substances and ___________ be broken down further by _____________ means
building blocks, cannot, chemical
. Because a few positively charged particles bounced back from the foil, Rutherford concluded that such particles were _____. a. striking electrons. c. repelled by densely packed regions of positive charge. b. indivisible. d. magnetic.
c
According to Dalton's atomic theory, atoms _____. a. are destroyed in chemical reactions. c. of each element are identical in size, mass, and other properties. b. can be divided. d. of different elements cannot combine.
c
An Avogadro's constant amount of any element is equivalent to ______. a. the atomic number of that element. c. 6.022 ´ 1023 particles. b. the mass number of that element. d. 100 g of that element.
c
An aluminum atom consists of 13 protons, 13 electrons, and 14 neutrons. Its mass number is _____. a. 13. b. 14. c. 27. d. 40.
c
An atom is electrically neutral because ______. a. neutrons balance the protons and electrons. c. the numbers of protons and electrons are equal. b. nuclear forces stabilize the charges. d. the numbers of protons and neutrons are equal.
c
Dalton hypothesized that atoms are indivisible and that all atoms of an element are identical. It is now known that ______. a. all of Dalton's hypotheses are correct c. atoms are divisible b. atoms of an element can have different numbers of protons d. all atoms of an element are not identical but they must all have the same mass
c
How is the number of neutrons in the nucleus of an atom calculated? a. Add the number of electrons and protons together. c. Subtract the number of protons from the mass number. b. Subtract the number of electrons from the number of protons. d. Add the mass number to the number of electrons.
c
How many moles of atoms are in 50.15 g of mercury (atomic mass 200.59 amu)? a. 0.1001 mol b. 0.1504 mol c. 0.2500 mol d. 0.4000 mol
c
In Rutherford's experiments, most of alpha particles pass through the gold foil undeflected. This result indicates ______. a. atoms were mostly empty space. c. both a and b b. atoms contained a tiny and dense nucleus d. none of the above
c
In water, H2O, the ratio of the masses of oxygen to hydrogen is 8:1. What is the ratio of the masses of oxygen to hydrogen in hydrogen peroxide, H2O2? a. 1:1 b. 8:1 c. 16:1 d. 32:1
c
Millikan's experiments ______. a. demonstrated that the electron carried no charge. c. measured the charge on the electron. b. demonstrated that the electron carried the smallest possible positive charge. d. demonstrated that the electron was massless.
c
Rutherford's experiments led to the discovery of the ______. a. electron. b. cathode ray. c. nucleus. d. neutron.
c
The atomic number of an element is 20. It is ______. a. chlorine b. oxygen c. calcium d. aluminum
c
The atomic number of neon is 10. The atomic number of calcium is 20. Compared with a mole of neon, a mole of calcium contains ______. a. twice as many atoms. c. an equal number of atoms. b. half as many atoms. d. 20 times as many atoms.
c
Which of the following elements exists as a diatomic molecule? a. neon b. lithium c. nitrogen d. sulfur
c
What did Thomoson's experiment show
cathode rays could be bent by magnets or electrically charged plates. Therfore the cathode ray is not a beam of light but it is a stream of tiny negatively charged particles moving at high speed
A carbon-13 atom (atomic number 6) has _____. a. 3 electrons and 3 neutrons. c. 6 protons and 7 electrons. b. 7 protons and 6 electrons. d. 6 protons and 7 neutrons.
d
An element has an atomic number of 76. The number of protons and electrons in a neutral atom of the element are _____. a. 152 protons and 76 electrons c. 38 protons and 38 electrons b. 76 protons and 0 electrons d. 76 protons and 76 electrons
d
Find the number of water molecules in 32.0 g of water a. 3.20 x 1024 b. 2.80 x 1024 c. 1.40 x 1024 d. None of the above
d
Given 1.00 mole of each of the following gases at STP, which gas would have the greatest volume? a. He c. N2 b. Omc060-1.jpg d. All would have the same volume.
d
If 4.0 g of element A combine with 10. g of element B, then 12. g of element A combine with ____ of element B. a. 10 g b. 12 g c. 24 g d. 30 g
d
If each atom of element D has 3.0 g and each atom of element E has 5.0 g,, a chemical DE molecule has _____. a. 15 g b. 2.0 g c. 35 g d. 8.0 g
d
Oxygen can combine with carbon to form two compounds, carbon monoxide and carbon dioxide. The ratio of the masses of oxygen that combine with a given mass of carbon is 1:2. This is an example of ______. a. the law of conservation of mass. c. the law of conservation of energy. b. Dalton's atomic theory. d. the law of multiple proportions.
d
The atomic mass of an element depends upon the ______. a. mass of each electron in that element c. relative abundance of protons in that element b. mass of each isotope of that element d. mass and relative abundance of each isotope of that element
d
The hydrogen isotope with the least mass is named ______. a. tritium. b. helium. c. deuterium. d. protium.
d
The nucleus of an atom _______. a. is positively charged. c. contains nearly all of the atom's mass. b. is very dense. d. all of the above
d
Which subatomic particle was discovered with the cathode ray
electrons
properties of isotopes
isotopes have the same chemical portperties but have different phyiscal properties.
summary of mole converstions
mole relates to mass, volume and number of particles . 1 mole = 22.4 L 1 mole = molar mass 1 mole = 6.02 x 10^23 # of particles
characteristics of electrons
negative charge, mass so small say it is 0, and it is outside the nucleous
which has a greater mass neutrons or protons
neutron
characteristics of neutrons
no charge, approximate mass is 1 amu inside nucleus
characteristics of protons
positively charged, approximated mass is 1 amu and is inside the nuclues
the number of protons is also
the atomic number
the discovery of electrons
the cathode rays are made up of a stream of megativley charged particles called electrons
mass before a reaction =
the mass after a reaction
definition of atomic mass
the mass of a single atom
By Millikan's experiment he concluded that
the mass of an electron is extremely small.
molar mass definition
the mass of one mole of a substance (compound or element)
Compare the size of an atoms and its nucleus
the nucleus is a very small part of the atom, making the atom mcuh larger than the nucelus itself
atomic number
the number of protons of an atom
definition of a atom
the smallest particle of an element that retain the characteristics of an element.
molecular mass definition
the total mass of all atoms present in a molecule of a covalent compund or a gaseous diatomic molecule
Formula Mass Definition
the total mass of all atoms presented in a formula unit of an iconic compound
molar mass of a compound
the total mass of all individual particles that made up the substance per mol
