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Atomic Structure
Terms relating to the structure of an atom
23
Chemistry
8th Grade
04/03/2010

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Cards

Term

 

 

atom

Definition

 

The smallest particle into which an element can be divided and still have the properties of that element.

 

 

 

Term

 

 

Dalton's Theory

Definition
Term

 

Thomson

Definition

  • small particles inside the atom. Thus, atoms can be divided into even smaller parts
  • negatively charged particles that Thomson discovered are now called electrons.
  •  a guess that the electrons were mixed throughout an atom, like plums in a pudding (plum-pudding model)

 

Term

 

 

Rutherford

Definition

  • tiny particles went straight through the gold foil. A small number of them were deflected. The explanation for this must be that most matter in an atom is found in a very small part of the atom
  • the center of the atom is a tiny, extremely dense, positively charged area called the nucleus
  • atoms are mostly empty space with a tiny, massive nucleus at the center.

Term

 

 

Bohr

Definition

  • electrons move around the nucleus in definite paths
  • electrons can jump from a path in one level to a path in another level

Term

 

Modern Atomic Theory

(Schrödinger & Heisenberg)

Definition

  • electrons do not travel in definite paths as Bohr suggested
  • exact path of an electron cannot be predicted
  • there are regions inside the atom where electrons are likely to be found. These regions are called electron clouds
  • Sometimes the regions are called orbitals
  • he energy of each electron in an atom keeps it in motion around the positive nucleus to which it is attracted.
  • electrons can move by gaining or losing energy, but they are never found between energy levels

Term

 

subatomic particles

Definition

  • particles that make-up an atom
  1. protons
  2. neutrons
  3. electrons

Term

 

 

nucleus of an atom

Definition

  • center of the atom
  • very dense
  •  (+) charged
  • contains protons and neutrons

Term

 

protons

Definition

  • (+) charged particles in the nucleus of an atom
  • also have mass

 

Term

 

 

amu

Definition

atomic mass unit

 

The SI unit that describes the mass of a particle of an atom

Term

 

neutron

Definition

  • particle in the nucleus of an atom
  • does NOT have a charge
  • does have mass

Term

 

electrons

Definition

  • (-) charged particles of an atom
  • found OUTSIDE the nucleus
  • so small, they have almost NO mass

Term

 

neutral atom

Definition

 

an atom with 0 charge

Term

 

ion

Definition

 

an atom with a charge

Term

 

atomic number

Definition

 

the number of protons in an atom

Term

 

isotope

Definition

 

Atoms that have the same number of protons but a different number of neutrons

Term

 

atomic mass

Definition

 

 

protons + neutrons 

Term

 

forces that hold atoms together

Definition

  • gravitational
  • electromagnetic
  • strong
  • weak

Term

 

gravitational force

Definition

 

very small in atoms because the particles in atoms are very small

Term

 

electromagnetic force

Definition

  • protons and electrons are attracted to each other because they have opposite charges
  • electromagnetic force holds the electrons around the nucleus

Term

 

strong force

Definition

  • force between protons
  • holds nucleus together
  • stronger than electromagnetic force

Term

 

weak force

Definition

  • in radioactive atoms
  • a neutron can change into a proton and an electron

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