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CA Chemistry-Atomic Structure
Atomic Structure
38
Science
10th Grade
10/02/2009

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Term

1. All matter is made up of tiny particles called atoms.

2. Atoms of the same element are chemically alike

3. Individual atoms of an element may not all have the same mass, but they have a definite average mass that is characteristic of that element

4. Atoms of different elements have different average masses

5. Atoms are not subdivided, created, or destroyed by ordinary chemical reactions

Definition
List the ideas of the Modern Atomic Theory
Term
Electron cloud
Definition
Most of the atomic radius is due to ___.
Term
nucleus
Definition
Most of the mass of the atom is located in the _____.
Term

electron

 

J.J. Thomson

 

cathode ray

Definition
The first subatomic particle to be identified was the _____, by _____, through the use of the ______.
Term

Rutherford

 

gold-foil experiment

Definition
That atoms have a small, dense, positively-charged nucleus was discovered by _____ when he performed his ______.
Term
True
Definition

True/False

 

The majority of an atom is empty space.

Term
nucleons
Definition

particles within the nucleus of an atom

(protons and neutrons)

Term

positive

 

relatively the same as a neutron

(1.673 x 10-27 kg)

 

nucleus

Definition
What is the charge, mass and location of a proton within an atom
Term

no charge

 

relatively the same as a proton

(1.675 x 10-27 kg)

 

in the nucleus

Definition
What is the charge, mass,  and location of a neutron in an atom
Term

 

negative

 

zero mass relative to p+ and n0

 

in electron cloud outside of nucleus

Definition
What is the charge, mass and locations of electrons in the atom?
Term
Nuclear forces
Definition
The short-range forces that hold nucleons together within the nucleus of an atom
Term
Atomic number
Definition
Indicates the number of protons in an atom
Term
Mass Number
Definition
indicates the total number of nucleons (protons and neutrons) within an atom
Term
# of protons
Definition
Bacause atoms are neutral, the number of electrons is equal to the _______.
Term
Isotopes
Definition
Atoms of the same element with different mass numbers due to their different number of neutrons
Term
nuclides
Definition
Atoms identified by the number of protons and neutrons in the nucleus
Term
Radioactive decay
Definition
the spontaneous disintegration of a nucleus into a slightly lighter and more stable nucleus, accompanied by emission of particles, EM radiation, or both
Term
Nuclear Radiation
Definition
particles or EM radiation emitted from the nucleus during radioactive decay
Term
#83
Definition

All nuclides beyond ____ are unstable.
Term
alpha particle
Definition

heavy-particle radiation that is made up of 2 protons and 2 neutrons (helium nucleus)

 

has a 2+ charge

 

danger and penetrations levels are low

 

 

 

 

Term
Beta particles
Definition

electron emitted from the nucleus during nuclear decay

 

emitted when neutron is converted into a proton and an electron

 

have a 1- charge

 

 

Term
gamma
Definition

high-energy EM waves emitted from a nucleus as it changes from an excited state to a ground energy state

 

Term
alpha emission
Definition
results in the reduction of a nucleus by 2 protons and 2 neutrons
Term
beta emission
Definition
results when a neutron breaks into a proton and an electron, causing the atomic number to increase by one
Term
gamma emission
Definition
type of radiation that almost always follows alpha and beta emissions
Term
radioisotopes
Definition
unstable isotopes prone to radioactive decay
Term
Neutron-to-proton ratio
Definition
determines the type of radioactive decay (if any) that occurs
Term
Band of stability
Definition
plotted on a neutron vs proton graph that indicates the stability of nuclides
Term
Half-life
Definition

the time required for half the atoms of a radioactive nuclide to decay

 

 

more stability=slower decay

Term
transmutations
Definition
a change in the identity of a nucleus as a result of a change in the number of its protons
Term
nuclear reactions
Definition
reactions that affect the nucleus of an atom
Term

E=mc2

 

E  = energy

m = mass

c = speed of light

Definition
Formula used to calculate the energy produced from mass conversions
Term
nuclear fission
Definition
occurs when a very heavy nucleus splits into more stable nuclei of intermediate mass
Term
Nuclear fission
Definition
transmutations reactions which always results in a loss of mass
Term
Nuclear chain reaction
Definition
a reaction in which the material that starts the reaction (such as a neutron) is also one of the products and can start another reaction
Term
critical mass
Definition
the minimum amount of nuclide that provides the number of neutrons needed to sustain a chain reaction
Term
nuclear fusion
Definition

occurs when light-mass nuclei combine to form a heavier, more stable nucleus

 

 

usually occurs at extremely high temperatures

Term

all man-made elements

 

all natural elements with an atomic number greater than 83

 

isotopes that vary from a 1:1 ratio of neutrons to protons

Definition
What elements are radioactive?
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