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Chemistry unit 3 test
Terms in this set (82)
What did Democritus say?
-Proposed the existence of an atom
What did Aristotle say?
-rejected the idea of the atom
- said matter could be cut continually
What was Dalton's theory proposed that atoms:?
- are building blocks of matter
- are indivisible
- of the same element are identical
- of different elements are different
-unite in small whole numbers ratios to form compounds
What did J.J Thomson say?
-credited with discovery of electron
- proposed the plum pudding model of the atom: negatively charged electrons embedded in a ball of positive charge
What did Rutherford's gold- foil experiment show:?
- aimed alpha particles at gold foil
-most passed through
- a few particles were defection
- some particles even bounced back
- most of the atom is empty dense, positively charged core (nucleus)
Diagram of J.J Thomson
chocolate chip cookie
Diagram of Bohr's
Diagram of Rutherford's
Who added four ideas to Democritus' atom?
What were john daltons four ideas
- Atoms of the same element are identical
- Atoms of different elements are different
- Atoms of different elements combine in simple whole-number ratios to form chemical compounds
-In chemical reactions, atoms are combined, seperated,and rearranged
The principles of the atomic theory were conceived by...
Experiments with cathode rays led to the discovery of the ?
What is the cathode ray tube?
The particles were negative energy do the atom was divisible it had the parts and pieces
According to Dalton's atomic theory, atoms
Of each element are identical in size, mass, and other properties
Who discovered the nucleus by bombarding gold foil with positively charged alpha particles ?
What did Rutherford conclude about the structure of an atom?
An atom contains a small, dense, positively charged central region( the nucleus)
Most of the volume of an atom is occupied by the
Isotopes are atoms of the same element that have different
An aluminum isotope consists 13 protons, 13 electrons, and 14 neutrons. Its mass number is
What is the Law of conservation of mass?
Matter cannot be created or destroyed only rearanged
What is the law of definite proportions?
2 parts hydrogen + 1 part oxygen + 1 part genus water=water
Who described 5 parts of an atomic theory
Found the electron
Discovered the nucleus
Was the first person to name the atom
Found the neutron due to missing mass in the atom
Said that the atom was mostly empty space
Used the gold foil experiment
Developed the Plum Pudding model
Developed the planetary model of the atom
Used the cathode ray tube experiment
What are the three subatomic particles (charge,mass, location)
Proton- positive, 1 amu, nucleus
Neutron- neutral, 1 amu, nucleus
Electron- negative, 0 amu, outside the nucleus
What is the atomic number?
Number of protons in an element (located at the top)
What is the mass number?
The total number of protons and neutrons in the nucleus
What is the Charge?
subatomic particles that determine the electromagnetic field
What is the electron number?
based off the charge
What did Chadiwck and Bohr contribute?
Bohr- planatry model
What in isotope?
Two atoms of the same element of protons with different numbers of nuetrons
What is the average atomic mass?
It is the decimal found on the periodic table
Average of all the masses of the isotopes of an element consuming the percentages in which naturally occure
did not believe in atoms and though all matter was continous
English chemist who developed the Atomic theory of matter through an experiment of gases
J J Thompson
discovered that atoms contain negatively charged particles or electrons
oil drop experiment, determined charge on an electron
gold foil experiment, proved that an atom is mostly empty space with a nucleus
model of atom in which electrons surround the positively charged nucleus as planets around the sun, in orbits
Democritus (460-370 BC) Contribution
first idea of atoms
Aristotle (384 - 322 BC) Contribution
said there were no atoms
Antoine Lavoisier (1743-1794) Contribution
Law of Conservation of Mass
Joseph Proust (1754-1826) Contribution (2)
1. Law of Definite Composition
2. Law of Definite Proportions
Joseph Proust (1754-1826) Particulars
(Law of Definite Composition and Law of Definite Proportions are the same thing) States that a chemical compound always contains exactly the same proportion of elements by mass
John Dalton (1766-1844) Contribution (2)
1. First atomic theory
2. Law of multiple proportions
J.J. Thomson (1856-1940) Contribution
J.J. Thomson (1856-1940) Particulars (4)
2. Negatively charged
3. Charge to mass ratio (coulombs/grams)
4. "Plum Pudding Model" model of atom
5. cathode ray experiment
Robert Millikan Contribution
determined charge on an electron
Robert Millikan Particulars
Ernest Rutherford (1911) Contribution
discovers the nucleus
Ernest Rutherford (1911) Particulars
1. Rutherford's Gold Foil Experiment
2. New model of atom: Nuclear Atom
James Chadwick (1932) Contribution
James Chadwick (1932) Particulars
2. neutral charge
Rutherford's Gold Foil Experiment (4)
1. Atom is mostly empty space - Most particles go straight through
2. Nucleus is positively charged, as are the alpha particles - Positive atoms coming to positive nucleus bounce off
3. Nucleus carries most of the atom's mass
4. Nucleus is very small - The chance the particle would bounce back is very unlikely
Electron cloud (4) vs nucleus (5)
1. mostly empty space
2. negatively charged (e^-1)
3. Defines shape, size of atom
4. Held in place by nucleus
2. Positively charged (e^+1, n^0)
3. Most of mass of atom
4. Tiny volume of atom
5. Attracts electrons
Dalton's Atomic Theory (4)
1) All matter is made of atoms. Atoms are indivisible and indestructible.
2) All atoms of a given element are identical in mass and properties
3) Compounds are formed by a combination of two or more different kinds of atoms.
4) A chemical reaction is a rearrangement of atoms.
-discovered the atom
-matter is empty space for atoms
-atoms are homogeneous,indestructible and invisible
-atoms do-not change when there is a change of matter, they are grouped differently
-discovered atomic theory
-all elements are composed of atoms (hard spheres)
-indestructible and invisible
-atoms of the same element are exactly alike
-atoms of different elements are different
-atoms combine in definite proportions by mass to form compounds
-atoms are rearranged in a reaction
-discovered the electron during cathode ray experiment
-atoms made of positively charged substances
- negatively charged electrons are scattered like RAISINS IN PLUM PUDDING
-a particle (electron) smaller than an atom existed
-the atom was divisible
-discovered the nucleus during the gold foil alpha particle experiment
-all of the positive charge,and most of the mass of an atom are concentrated in a small core,called the nucleus
-the negatively charged particles were scattered outside the nucleus
-discovered energy levels
-electrons move in different orbits around the nucleus
-the energy levels are located at a certin distance from the nucleolus.
-atoms are mostly empty space but the nucleolus
Quantum & Heisenberg
-discovered electron cloud through many different experiments
-electrons do not have a planetary orbit, instead the location of an electron is described as a probability(not a fixed position)
a atom has a small positively charged nucleus surrounded by a large electron cloud region (probable locations for electrons
-discovered electron charge during the oil drop experiment
-the quantitative charge on the electron as calculated by Millikan-1.592x10-19 coulomb
Atoms that have the same number of protons and different number of neutrons
Isotopes of an element have a
different mass number (and number of neutrons)
How do you write isotopes?
element name-mass #
how to calculate average atomic mass
1. multiply percent abundance by mass of isotope
2. add values together
3. divide by 100
calculate the average atomic mass
Boron-10: 19.78 x 10 = 197.8
Boron-11: 80.22 x 11 = 882.42
197.8 + 882.42 = 1080.22
Arrangement of electrons in the orbitals of an atom.
Electrons in the outermost energy level of an atom, they are involved in bonding
Noble gas notation
a way of writing the electron configuration of an atom that uses a nearby, prior noble gas (with a full octet) as a starting point
Designated s, p, d, f, according to the way electrons orbit in these groups
Electrons must occupy the lowest energy level posible
orbitals of the same energy level each get one electron before any get two
Pauli's exclusion principle**
no two electrons can have the same 4 quantum numbers
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