Science term 1 year 9

• Who improved our understanding of electrons in an atom?

  Neils Bohr
• What did Neils Bohr conclude about electrons?

  Electrons orbit the nucleus at specific distances
• What is the equation for isotopes abundance

  
  

  mass x %|100
• What did Mendeleev do in his periodic table?

  He left gaps for undiscovered elements and predicted their properties
• How did Mendeleev group some elements in his periodic table?

  He grouped elements with similar properties together
• By what criteria was Mendeleev's periodic table ordered?

  By atomic weight
• How is the modern periodic table arranged?

  By increasing atomic number
• What are columns in the periodic table called?

  Groups
• What are rows in the periodic table called?

  Periods
• What are the general properties of metals?

  • Shiny
  • Hard and strong
  • High density
  • High melting point
  • Good thermal conductor
  • Good electrical conductor
• What are the general properties of non-metals?

  • Dull
  • Soft, brittle, or gas
  • Low density
  • Low melting and boiling points
  • Poor thermal conductor
  • Poor electrical conductor
• What is the decay equation for Alpha decay?

  Rn → He
• What is the decay equation for Beta decay?

  C → N + e
• What is half-life?

  It is the time it takes for half the nuclei in a radioactive substance to decay
• What is a mixture?

  • Consists of two or more different elements or compounds
  • Not chemically combined together
• What is filtration used for?

  To separate an insoluble solid from a liquid
• Why can solid particles be separated by filtration?

  Because solid particles are too large to fit through the tiny holes of the filter paper
• What is crystallisation used for?

  To separate a soluble solid from a liquid
• How does crystallisation work?

  The liquid evaporates to leave crystals of the solid
• What is distillation used for?

  To separate a liquid from a solution
• How does distillation work?

  The liquid is heated and evaporates, then condenses again when cooled
• What is the diameter of an atom?

  $1 \times 10^{-10} \text{ m}$
• What is the diameter of a nucleus?

  $1 \times 10^{-14} \text{ m}$
• What is the formula for magnification?

  Magnification = image size ÷ actual size
• What are the relative charges and masses of protons, neutrons, and electrons?

  • Protons: +1 charge, mass 1
  • Neutrons: 0 charge, mass 1
  • Electrons: -1 charge, very small mass
• What is the plum pudding model of the atom?

  • A ball of positive charge
  • Embedded with negative electrons
• What were the findings of the alpha particle scattering experiment?

  • Most alpha particles went straight through
  • Suggests the atom is mostly empty space
  • Some were deflected at large angles
  • Mass is concentrated in the center of the atom
  • The nucleus is positively charged
• What is an Alpha particle?

  A helium atom with 2 protons and 2 neutrons
• What is the charge and atomic mass of an Alpha particle?

  Charge is +2 and atomic mass is 4
• What is a Beta particle?

  A high energy electron with a charge of -1
• What is the mass of a Beta particle?

  Very small
• What is a Gamma particle?

  A high energy electromagnetic wave with charge and mass of 0
• Who discovered the neutron?

  James Chadwick
• What are the main components of a cell?

  • Nucleus
  • Permanent vacuole
  • Cell membrane
  • Ribosome
  • Chloroplast
  • Mitochondria
  • Cytoplasm
  • Cell wall
• What does the nucleus do in a cell?

  It contains DNA and controls the activities of the cell
• What is the function of the cell membrane?

  It controls the movement of substances in and out of the cell
• What is the role of the cell wall?

  It provides strength and structure
• What happens in the cytoplasm?

  Most chemical reactions take place
• Where is most of the energy released in a cell?

  In the mitochondria through respiration
• What is the function of ribosomes?

  Protein synthesis