Test 3- Atomic Theory Flashcards
Antoine Lavoisier main
Law of conservation of matter
Joseph Louis Proust main
- Law of Composition
- Law of Multiple Proportions
- Combustion reactions
John Dalton
- Atomic Theory of Matter
- solid sphere model
Sir William Crookes
- Cathode Ray Tube
J.J. Thompson
Plum pudding model
Robert Milikan
Oil drop
Determined mass and charge of an electron
Henri Bacquerel
Photographer
Ernest Rutherford
- Two experiments:
- Isolated and identified alpha, beta and gamma radioactive emissions
- gold foil experiments, and
- Planetary model
Aristotle
Thought everything was made up of 4 elements- earth, air, water, and fire. Also, student of Plato
Democritus
Student of Aristotle but thought that he was wrong. Thought that everything was made up of Atoms- “indivisible” in Greek. 400 BCE
Between these philosophers and the modern exploration of matter
was something called Alchemy- the making of gold
Antoine Lavoisier
- Late 1700’s
- Father of Chemistry
- Worked in lab and took quantitative data
- Figured out that the mass of reactants=mass of products
- Law of Conservation of mass (matter)- matter can not be created or destroyed in any chemical reaction.
- E=mc^2 (Einstein) where E=energy, m=mass, and c^2=speed of light. I have no idea how this related to anything but it was in out notes ☺
Joseph Louis Proust
- 1799
- Law of Constant proportion/Law of definite composition- The ratio of the elements in a compound remains the same. Ex. Water always has 2 hydrogen and 1 oxygen.
- Law of Multiple Proportions- Same element can be in different compounds as long as ratio changes. Ex. H2O= 2:1 while H2O2= 1:1
Law of Constant proportion/Law of definite composition-
The ratio of the elements in a compound remains the same. Ex. Water always has 2 hydrogen and 1 oxygen.
Law of Multiple Proportions-
Same element can be in different compounds as long as ratio changes. Ex. H2O= 2:1 while H2O2= 1:1
Combustion reactions
- C X Hy+O2⇒CO2+H2O
- C4H10+a lot and C8H18+a lot⇒complete combustion
- C X Hy+O2 (limited)⇒CO+H2O (incomplete combustion)
- C X Hy+O2 (less O2 than above)⇒C+H2O (incomplete combustion)
- ⇒Yield sign, points to direction of reaction
John Dalton
- 1803
- Atomic Theory of Matter:
1. Each element is composed of extremely small particles called atoms (Democritus)
2. All atoms of the same element are identical in chemical and physical properties, but differ from those of any other element.
3. Atoms are neither created nor destroyed. Chemical reactions consist of the combination, separation, or rearrangement of atoms (Lavoisier)
4. A given compound always has the same relative number and kinds of atoms (Proust) - Soil Sphere model
The Atomic Theory of Matter-John Dalton
- Each element is composed of extremely small particles called atoms (Democritus)
- All atoms of the same element are identical in chemical and physical properties, but differ from those of any other element.
- Atoms are neither created nor destroyed. Chemical reactions consist of the combination, separation, or rearrangement of atoms (Lavoisier)
- A given compound always has the same relative number and kinds of atoms (Proust)
Sir William Crookes
- 1870s
- Cathode Ray Tube
- Crookes noted that the green glow moved with a magnet and moved a paddle wheel
J.J. Thompson
- Identified negative component in matter and deduced that there must be a positive part because matter is neutral
- Dalton was wrong about model of atom. Thompson proved the presence of electrons
- Plum pudding model/sea of electrons model- number of number of P+= number of e-
Robert Millikan
- Oil Drop experiment
- Determined the mass and change of an electron
Henri Becquerel
- Photographer
- Photographed uranium- a radioactive rock and noticed exposure
Ernest Rutherford- Radioactive emissions
- Isolated and identified alpha, beta and gamma radioactive emissions
- 3 types of radioactive emissions
- Ex. Of Alpha decay: 238(92)U⇒4(2)α+234(90)Th
- Example of Beta Decay: 214(82)Pb⇒214(83)Bi+0(-1)β
- Beta decay- neutron changes into a proton (stays in nucleus) and electron (β particle) that flies away.
- Rutherford determined alpha and Beta particles
- Gama in energy not a particle
Ernest Rutherford-Gold Foil
- Gold foil experiment: A ray of gama particles was shot through a piece of gold foil with photo film around it. Most of the exposure was directly across showing that most of the particles went straight though. However, some of the particles deflected showing that it bounced off something (nucleus)
- The particles were positive so since the particles deflected, this means that the nucleus is positive since the same charge repels each other.
- Since most of the rays went straight through, this showed that it was mostly empty space.
- Three conclusions:
1. Atoms have a nucleus
2. The nucleus is positive
3. Mostly empty space
Ernest Rutherford- Atomic model
- Model number 3 proposed by Rutherford
- Planetary model
- Move in circles so they don’t stick to Nucleus
- Like an amusement park ride
Evolution of models of the atom
- Three models: Solid sphere, plum pudding, and planetary.
- The first was solid sphere. Proposed by John Dalton before experiments like the cathode ray tube were done to find out what was inside an atom.
- The second was the plum pudding/sea of electrons model. J.J. Thompson proposed this. He set up another cathode ray but with metal plates on the top and bottom. When the rays moved toward the positive part, he deduced that there must be a positive part since matter is neutral. He therefore identified negative component in matter, proving Dalton wrong. Protons=electrons.
- The third model is called the planetary model proposed by Ernest Rutherford. He said that electrons move in circles around the positively charged nucleus so that they don’t stick together.
Subatomic Particle- Relative charge
Proton- +1
Neutron- 0
Electron- -1
Subatomic Particle- Mass number
Proton- 1
Neutron- 1
Electron- 0
Subatomic Particle- Nuclear symbol
Proton- 1(1)P; 1(1)H; P+
Neutron- 1(0)n or n°
Electron- 0(-1)e or e-
Subatomic Particle- location
Proton- Nucleus
Neutron- Nucleus
Electron- Around the nucleus but still inside the atom
Relative mass
atomic mass unit (amu) is 1/12 the mass of a carbon-12 atom
Nuclear symbol
mass P+n(# of P)X
Nucleus-
P+ and n°- also called nucleons
Number of protons is called
the atomic number
Element is defined by
Number of protons
Mass number=
P+ + n°
Electrons are equal to
the number of Protons
bottom nuclear symbol
- Atomic number
- Number of protons
- Number of electrons (unless ion)
Top of nuclear symbol
Mass number
How to find the number of neutrons
mass # - # of protons
In 14(6)C there are
- 6 protons
- 6 electrons
- 8n(14-6)
If given something like C-12
- 12 is the mass number.
- You know there are 6 Protons because its carbon, therefore there are 6 electrons.
- There is 6 neutrons since 12-6=6
Isotope
An atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass) Ex. C-14 and C-12
Ion
- An atom that has lost or gained electrons
- Gained electron-Anion-Negatively charged
- Lost election-Cation-Positively charged
86(37)Rb+2
The +2 tells us that its an ion. Since its positive, it has a positive charge which means that is loses electrons. P+=37, n°=49, and e-=35 (37-2)
Nucleons
protons and neutrons
Electrostatic attraction
Protons and electrons attract
Electrostatic repulsion
e-+e- and P+P repel
(Strong) Nuclear force
the interaction that binds P+n, P+P, and n+n in nucleus.
A nucleus is stable when
nuclear force and electrostatic repulsion balance out. This occurs when the ratio of n to P is between 1:1 and 1.5:1. This is also called the band of stability
No more than ___ protons before nucleus is unstable (radioactive)
- 83
- so Bismuth is ok but starting with Polomium, its not.
Nuclear Reaction
A change in the nucleus of an atom
Chemical Reaction
Atoms are just rearranged/combined, not changed
Transmutational Reaction
Change in identity of a nucleus as a result of the number of protons changing.
Alpha particle emissons
- Rutherford-radioactive particles- Alpha particles:
- 4(2)α- 2P and 2n from nucleus
- Ex. 238(92)U⇒4(2)α (leaves nucleus)+ 234(90) Th. This is an example of Radioactive decay and Tansmutation
Radioactive decay happens
spontaneously and by itself
Beta particle emissions
- Beta particles- n° changes into P+ and e-, P+ stays, e- is emitted
- Ex. 214(82)Pb⇒214(83)Bi + 0(-1)β. Notice how the bottom number changes as one neutron is changed into a proton, changing the element since the number of protons determines the element.
Nuclide
atom, but in nuclear activity
radioactive decay
spontaneous disintegration of a nucleus into a slightly lighter nucleus accompanied by emission of particles, electromagnetic radiation, or both. Both α and β are examples of radioactive decay
Gamma emissions
Gamma is the electromagnetic radiation that’s given off.
Health risks-
Alpha-low, Beta-medium, Gama-high
Half life
The time required to half of the atoms of a radioactive sample to decay.
Formulas for half-life:
- Number of half-lives=time elapsed X 1 half-life/14.3 days
- Amount remaining= original amount X ½ for each half-life
Fusion
Low-mass nuclei combine to form a heavier, more stable nucleus. Ex. Nuclear reactions
Fission
A very heavy nucleus splits into more stable nuclei of intermediate mass. Ex. Sun, atomic bombs
Fission and Fusion are both
not spontaneously forced
E=mc^2
- nuclear reaction energy formula
- Einstein
Experiments with cathode rays (crooks tube) being deflected by a magnetic fields show that cathode rays are composed of particles that are.
-Magnetic (because its Crooks and he didn’t know about negative charge yet)
Cathode rays are composed of particles that are now known as
-Electrons
In 1911, Ernest Rutherford conducted his now famous gold foil experiment. During the experiment, alpha particles bombarded a thin piece of gold foil. The alpha particles bombarded a this piece of gold foil. The alpha particles were expected to pass easily through the gold foil. Every now and then, however, an alpha particle bounced back- an unexpected result. Rutherford concluded that these particles were striking:
-A tiny region of particle charge
Rutherford called the region that deflected alpha particles:
A nucleus
The total volume of the nucleus of an atom is:
-Very small compared with the rest of the atom
Why did the mass increase in the open container?
-As matter burns, the oxygen in the air combines with the matter, adding to its overall mass. In the closed container, there was very little and limited oxygen to combine with the matter, so the mass did not increase, but remained the same due to the law of the conservation of matter.
Ion
an atom, radical, or molecule that has gained or lost one or more electrons and has a negative or positive charge
atom
the smallest unit of an element that maintains the chemical properties of that element
