mass unit test
How many protons are in an atom with an atomic number of 20, an atomic mass of 45, and a charge of +2?
20
If an atom has 10 protons, 10 neutrons, and 10 electrons, what is the mass of the atom?
20
What is the molar mass of sodium?
22.990
How many grams is 1.2 moles of Neon?
24 grams
How many neutrons are in an atom with an atomic number of 20, an atomic mass of 45, and a charge of +2?
25
The number 6.02 x 1023 is called...
Avogadro's number
an atom of nitrogen has 7 protons and 7 neutrons
ST
Atoms of different elements are exactly alike
always false
The smallest particle of an element that still retains all the properties of that element.
atom
Isotopes have a different what?
atomic mass
In Dalton's Atomic Theory, all elements consist of __________ that cannot be divided.
atoms
Which idea of Dalton's is no longer considered part of the modern view of atoms?
atoms of the same element have identical masses
Who is the scientist who proposed the "solar system" model of an atom where the electrons orbit around the nucleus?
bohr
One Atomic mass unit is defined as 1/12th the mass of one
carbon -12 atom
According to Dalton's Atomic Theory, ______________ (like water) are formed when two or more elements combine in a given ratio.
compounds
The law of conservation of mass states that mass cannot be
created or destroyed
Who is credited with developing the atomic theory? (Sometimes called the father of atomic theory)
dalton
The law of ___ proportions says that atoms combine in specific whole number ratios.
definite
The first person to ever talk about an atom was
democritus
J.J. Thomson used a cathode ray tube to find what particle in the atom?
electron
JJ Thompson's discoverd what?
electron
The cathode ray experiment proved the existence of which subatomic particle?
electron
Ernest Rutherford discovered that atoms were mostly _________________.
empty space
The nucleus is made up of protons and what other particle?
neutrons
What can you conclude from the fact that scientists continue to update the atomic model?
new information about atoms continue to be discovered
Nitrogen has three occurring isotopes: Nitrogen-13, Nitrogen-14, Nitrogen-15. Which isotope is the most abundant?
nitrogen-14
Rutherford's model of the atom introduced the _________.
nucleus
the gold foil experiment proved the existence of which subatomic particle?
nucleus
this contains most of the mass of an atom
nucleus
What is the atomic number?
number of protons
What is the mass number?
number of protons and neutrons
Bohr's planetary model involved the electrons residing in ____________.
orbitals
Where do you look to calculate the molar mass?
periodic table
Rutherford's experiment determined that the nucleus of an atom is tiny, dense and ______ charged.
positively
Isotopes all have the same number of ___________
protons
What subatomic particles would you find in the nucleus of an atom?
protons and neutrons
Which subatomic particles contribute the most to the mass of an atom?
protons and neutrons
Which has a greater mass: 1 mole of scandium or 2 moles of boron?
scandium
This model was developed after J.J. Thompson discovered electrons, a particle smaller than an atom. Is shows electrons floating freely in a positive space.
the "plum pudding model" of the atom
This model this model was the first to show a nucleus, consisting of protons and neutron. Electrons surround the nucleus but are not shown in distinct energy levels.
the "rutherford model" of an atom
This model added on to previous models by showing electrons existed at certain "energy levels". However is does not accurately show what those levels look like.
the "solar system model" of the atom
The Plum Pudding Model belongs to which scientist?
thomson
Protons and Electrons balance the charge of an atom.
true
James Chadwick discovered this particle.
neutron
What subatomic particle is electrically neutral (no charge)?
neutron
An element has two naturally occurring isotopes. One is 10.013 amu and is 19.9% abundant. The other is 11.01 amu and is 80.1% abundant. What is the average atomic mass? What element is it?
10.812, Boron
If an atom has 12 positively charged subatomic particles, which of the following must it also have to be considered a neutral atom?
12 electrons
What is the mass number and name of an element with 8 protons and 8 neutrons
16- oxygen
Which is the correct sequence of the scientists who made major changes in the model of the atom? 1-JJ Thomson 2-Erwin Schrodinger 3-John Dalton 4-Niels Bohr 5-Ernest Rutherford
3,1,5,4,2
The mass number of an element that has 18 protons, 18 electrons, and 19 neutrons is _____.
37
Lithium with atomic # 3 and mass number of 7 has how many neutrons?
4
How many moles are 2.85 x 1018 atoms of iron?
4.73 x 10-6 moles
Which conversion factor would you use to calculate correctly the mass of 2 moles of the element titanium?
47.87 g Ti / 1 mol Ti
How many atoms are in 8.5 mole of nickel?
5.1 * 1024 Ni atoms
How many atoms of iodine are in a mole of iodine?
6.02 x 1023
Carbon 14 has how many neutrons?
8
atoms of elements are electrically neutral
AT
relative atomic masses are measured in amus
AT
the charge on all protons is the same
AT
according to dalton's atomic theory, atoms are composed of protons, electrons, and neutrons
NT
the atomic number of an element is the sum of the protons and electron in the atom
NT
the atomic number of an element is the whole number that decreases as you read each row of the periodic table from left to right
NT
the mass of an electron is equal to the mass of a neutron
NT
Which statement best describes the locations of the subatomic particles?
The protons and neutrons are in the nucleus, while the electrons are in the cloud outside the nucleus
In chemistry, a "mole" is:
a large number used to count particles
What element contains 26 protons?
iron
Ag--110 and Ag--112 are two forms of silver with different mass # so they are
isotopes
The fact that matter is not created or destroyed in any chemical or physical change is called the _______.
law of conservation of mass
Which law supports the example that water is always make up of 2 g of hydrogen to 16 grams oxygen?
law of definite proportions
Which law would support the example of CO having 12 g C to 16 g oxygen and CO2 having 12 g C and 32 g oxygen
law of multiple proportions
In Dalton's Atomic Theory, atoms of a particular element have the same ___________.
mass
The law of ___ proportions states that atoms of the same types of elements can combine in different whole number ratios.
multiple
electrons have this type of charge?
negative
An atom's overall charge is ________.
neutral