Science

• 1. Period is a term is used to describe the horizontal rows in the periodic table.
  2. Dmitri Mendeleev credited the modern periodic law, which states that the properties of elements are a periodic function of their atomic numbers.
  3. In the reactivity series of metals, Sodium is the most reactive.
  4. Semimetals are often used in the manufacturing of Semiconductors.
  5. Alkali metals is the common name for Group 1 elements in the periodic table.
• 1. Metals at the bottom are less reactive.
  2. Why are the elements bromine, chlorine and iodine placed in the same group of the Periodic Table because They have the same number of electrons in their outer shell.
  3. poor conductors of electricity is typically a property of non-metals.
  4. Boron is a semi metals which have the appearance and some properties of a metal but behave like a nonmetal in certain instances.
  5. With respect to position in the periodic table of the representative elements, the metallic property is increasing from top to bottom.
• Elements within the same group in the periodic table

  Have similar properties because they have the same number of valence electrons
• Periodic Table

  • Elements are arranged by their atomic number from left to right and from top to bottom
  • As we go from left to right across period, electron affinity increases
• Deflection of alpha particles is a phenomenon that Rutherford's gold foil experiment confirm, supporting the nuclear model of the atom
• Planetary model


  Nucleus is at the center of the atom, analogous to the sun in a solar system
• Strong nuclear force


  A force responsible for holding protons and neutrons together in the nucleus
• As the alpha particle gets closer to the positively charged nucleus

  The trajectory will be deflected and repelled
• Atom


  The smallest unit and the building block of matter
• John Dalton proposed that matter could not be divided into smaller pieces and was made of small, hard particles called "atoms"
• Electron


  The lightest subatomic particle and carries a negative charge
• Joseph John Thomson is the scientist behind the discovery of electron
• Atomic number of an element

  Tells the number of protons that it has in its nucleus
• Isotopes of an element

  Differ in the number of neutrons
• The power cable is loose. What is the solution?

  Secure the power cable