Chem Atoms quiz

neutron

(1,0 n )

John Dalton

(1808) created the very first atomic theory. Dalton was an English school teacher who performed many experiments on atoms. Dalton viewed atoms as tiny, solid balls.

JJ Thomson

(1897) discovered electrons. He was the first scientist to show that the atom was made of even smaller things.He also proposed the existence of a (+) particle... His atomic model was known as the "raisin bun model"... Thomson knew that electrons had a negative charge and thought that matter must have a positive charge. His model looked like raisins stuck on the surface of a lump of pudding.

Ernest Rutherford

(1911) discovered protons and the nucleus. He showed that atoms have (+) particles in the center, and are mostly empty space. He called these (+) particles protons. He called the center of atoms the nucleus.

Niels Bohr

(1913) improved on Rutherford's model. He proposed that electrons move around the nucleus in specific layers, or shells. Every atom has a specific number of electron shells.said the electrons do not spiral into the nucleus and came up with some rules for what does happen

James Chadwick

(1932) discovered neutrons. Working with Rutherford, he discovered particles with no charge .He called these particles neutrons. Neutrons are also found in the nucleus.

modern atomic model

(1932-) Work done since 1920 has changed the model. The new atomic model has electrons moving around the nucleus in a cloud. It is impossible to know where an electron is at any given time.

Average Atomic Mass=

(isotope 1 mass * percent abundance) + (isotope 2 mass * percent abundance) + (isotope 3 mass * percent abundance)

What is the mass of a neutron?

1 amu

Dalton atomic theory

1. Atoms are tiny, invisible particles. 2. Atoms of one element are all the same. 3. Atoms of different elements are different. 4. Compounds form by combining atoms.

Milikan

1909, american physicist successfully measured the charge and mass of an electron -performed the oil drop experiment

fission

A nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy. "a splitting or breaking up into parts"

Positron (β+):

A positron is the antimatter version of an electron. This particle is released when a proton turns into a neutron.

Proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom (1/1 H)

atom

A unit of matter, the smallest unit of an element, consisting of a dense, central, positively charged nucleus surrounded by a system of electrons, equal in number to the number of nuclear protons, the entire structure having an approximate diameter of 10-8 centimeter and characteristically remaining undivided in chemical reactions except for limited removal, transfer, or exchange of certain electrons.

isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

JJ Thomson model

Atoms are made mostly out of (+) charged material, like dough in a bun. The (-) charged electrons are found inside the (+) dough.

Fusion

Creation of energy by joining the nuclei of two hydrogen atoms to form helium. "a merging of separate elements into a unified whole". Nuclear fusion refers to the "union of atomic nuclei to form heavier nuclei resulting in the release of enormous amounts of energy"

Atomic Theory Timeline

Democritus, Dalton, Thomson, Millikan, Rutherford, Bohr,Chadwick, Modern

mass of electrons and neutrons

Electrons = 0 amu (the mass is negligible) Neutrons = Mass number (round to a whole number) - Atomic Number

Radiation

Emission of electromagnetic rays or subatomic particles.

Gamma ray penetrating power

Gamma rays are a radiation hazard for the entire body. They can easily penetrate barriers that can stop alpha and beta particles, such as skin and clothing. Gamma rays have so much penetrating power that several inches of a dense material like lead, or even a few feet of concrete may be required to stop them.

Rutherford's used elements

He knocked hydrogen nuclei out of atoms of six elements: boron, fluorine, sodium, aluminum, phosphorus, an nitrogen. He named them protons, from the Greek for 'first', for they consisted of the first identified building blocks of the nuclei of all elements. He found the protons mass at 1,836 times as great as the mass of the electron.

Rutherford's experiment

He though thought it would prove interesting to bombard atoms with these alpha rays, figuring that this experiment could investigate the inside of the atom (sort of like a probe). the experiment that proved the nucleus must be positively charged (as alpha particles were scattered/deflected by a piece of gold foil). Most α particles went through the gold. The atom is mostly empty space. The atom had a very dense (+) center, Rutheford called it the nucleus.

Neutrons

Mass number - Atomic Number. When calculating neutrons round the atomic mass to the nearest whole number to find the mass number. This is the most common isotope

Milikan's Experiment

Oil drop experiment, determined the size of the charge on an electron. He also determined that there was a smallest 'unit' charge, or that charge is 'quantized'.

fission simplified

One atomic nucleus splits to form two or more new nuclei.

atomic structure

Protons and neutrons are located in the nucleus. Protons = 1 amu Neutrons = 1 amu

Bohr rules

RULE 1: Electrons can orbit only at certain allowed distances from the nucleus. RULE 2: Atoms radiate energy when an electron jumps from a higher-energy orbit to a lower-energy orbit. Also, an atom absorbs energy when an electron gets boosted from a low-energy orbit to a high-energy orbit.

Calculating Average Atomic Mass

The atomic mass listed on the periodic table is an average of all known isotopes.

current atomic model

The new atomic model has electrons moving around the nucleus in a cloud. Chemistry is based on the modern atomic theory, which states that all matter is composed of atoms. Atoms themselves are composed of protons, neutrons, and electrons. Each element has its own atomic number, which is equal to the number of protons in its nucleus.

Radiation occurs when an atom's nucleus changes.

The new particle is called a daughter isotope.

Half Life

The time it takes for half of a parent isotope to decay to its daughter isotope.

fusion simplified

When the nuclei of two different atoms combine to form one new nucleus

Alpha penetrating power

alpha particles have a very limited ability to penetrate other materials. They can be blocked by can be blocked by a sheet of paper, skin, or even a few inches of air.

Three types of radiation due to nuclear decay are

alpha, beta and gamma.

fusion occurs when

atoms are under immense pressure (like in the center of the sun). Elements up to Iron (26) can be formed in stars. This process releases energy.

nucleus of an atom

contains all of the mass of the atom but nearly none of the volume.

Atomic number:

equal to the number of protons in the nucleus, as well as the number of electrons in the electron cloud.

Isotopes

isotopes are different versions of the same element. Each isotope has a different number of neutrons.

when fission is not controlled

it creates a nuclear bomb. 236U→ 142Ba + 91Kr + 3 1n

Nuclear fission takes place when

large, somewhat unstable isotope (atoms with the same number of protons but different number of neutrons) is bombarded by high-speed particles, usually neutrons. These neutrons are accelerated and then slammed into the unstable isotope, causing it to fission, or break into smaller particles.

the longer the half life, the __________ stable nuclide

more

Electrons exist in a

probabilistic cloud.Electrons are "wave-particles" their charge is located at a single point when measured but at any time can be found somewhere in the cloud (orbital). The electrons contain nearly no mass but nearly all the volume.

which subatomic particles ass mass to an atom

protons and neutrons

mass number:

sum of the number of protons and neutrons in a specific isotope

atomic mass

the weighted average of the masses of the isotopes of an element. Rounding the atomic mass to the nearest whole number yields the mass number of the most common isotope.

Democritus

was a Greek philosopher (470-380 B.C.) who is the father of modern atomic thought.He proposed that matter could NOT be divided into smaller pieces forever. He claimed that matter was made of small, hard particles that he called "atomos"

(β+)Beta positive (positron)

when antimatter is released when a proton turns into a neutron

fission occurs

when certain atom's nucleus is struck by a neutron. This process can be controlled to create vast amounts of energy in nuclear power plants.

beta negative decay β-

when electrons are released from the nucleus when a neutron turns into a proton

The resulting daughter isotope of alpha radiation

will have an atomic mass of 4 less than the parent and an atomic number of 2 less.

Alpha Radiation

α: the emission of two protons and two neutrons. Alpha radiation is the same as a helium atom and has a 2+ charge.

Beta Radiation

β: There are two types of beta radiation Electron (β-). This particle gets release from the nucleus when a neutron turns into a proton.

Gamma Radiation

𝛾: High energy electromagnetic radiation. This often follows beta and alpha radiation. Atoms in excited states will relax and release gamma rays. Gamma rays are also produced when electrons and positrons collide and annihilate.