1ST Q - ELECTRONICS

• Atoms - Smallest particle of an element.
• Nucleus - Located at the center of the atom.
• The nucleus contains positively charged particles called protons and uncharged particles called neutrons.
• Electrons - Negatively charged particles that orbit around the nucleus.
• Parts of an atom:

  • Protons
  • Neutrons
  • Electrons
• Identify the parts of the atom

  A) electrons

  B) neutrons

  C) nucleus

  D) orbit

  E) protons

  
• Atomic Number - The number of protons in the nucleus of the atom in the element.
• Atomic Weight - Mass of the atom.
• Atomic Weight - It is determined by the total number of protons and neutrons in the nucleus.
• Electrons orbit in concentric circles about the nucleus.
• Shell - Each orbit is called by this.
• Shells are filled in a sequence:

  1. K
  2. L
  3. M
  4. N
  5. O
  6. P
  7. Q
• Valence Shell - It is the outer shell
• Valence - Number of electrons it contains
• The farther the valence shell is from the nucleus, the less attraction the nucleus has on each valence electron.
• The potential for the atom to gain or lose electrons increases if the valence shell is not full and is located far enough away from the nucleus.
• The number of electrons each shell can accommodate: 2, 8, 18, 32, 18, 12, 2.
• The number of electrons each shell can accommodate:

  A) 2

  B) 8

  C) 18

  D) 32

  E) 18

  F) 12

  G) 2

  H) K

  I) N

  J) q

  
• Protons - Positively charged particles
• Neutrons - Uncharged particles
• Electrons - Negatively charged particles
• Free Electrons - This is what electrons become when appropriate external force is applied to electrons in the outermost shell, they are knocked loose.
• Current - The movement of free electrons
• As it travels along its path, the current encounters some opposition, called resistance.
• Voltage - The external force needed to create this current
• Matter - Anything that occupies space and has weight.
• Three States of Matter

  • Solid
  • Liquid
  • Gas
• Matter can be an element or a compound.
• Elements - Basic building blocks of nature.
• Elements - It is a substance that can't be reduced to simpler substance by chemical means.
• Examples of Elements:

  • Gold
  • Silver
  • Copper
  • Oxygen
• Compound - A substance that contains two or more elements chemically combined in fixed proportions.
• Compound - This can be separated by chemical but not by physical means.
• Examples of Compounds:

  • Water (hydrogen and oxygen)
  • Salt (sodium and chloride)
• Molecule - Smallest part of the compound that still retains the properties of the compound.
• Molecule - This is a chemical combination of two or more atoms.
• Mixture - Physical combination of elements and compounds.
• Conductivity of an atoms depends on its valence band.
• The greater number of electrons, the less it conducts.
• Conductors - Materials that contain large number of free electrons