Science

• Technology is the application of Science where scientific discoveries are made.
• Three misuses if Science are: pollution, over exploitation of natural resources and the invention of deadly weapons that are harmful to use
• For parallelogram Area=bxh
• Rhombus area=1/2 (a+b)x h
• Circle area=pi radius (3.14)²
• Cube volume=S³
• Cuboid volume=l x w x h
• Cylinder volume=pi radius (3.14) x h
• Cone volume=1/3 x pi r² x h
• • Diffusion- The movement of molecules from an area of high concentration to an area of low concentration
• Osmosis- The movement of water molecules from a region of high water concentration to a region of low water concentration (it makes both regions have the same water concentration). When there is more solute on one side of the membrane the water molecules are packed closer together than the opposing side of the membrane.
• Semi-permeable membrane: A membrane that only allows some substances to pass through it
• Elements with chemical symbols from Latin names


  • Na for sodium (from natrium)
  • etc...
• Oxygen, carbon, hydrogen, and nitrogen together make up about 96% of the human body
• Chemical symbol


  Designation for each element, usually a single capital letter or a combination of two letters
• Gold atoms cannot be broken down into anything smaller while still retaining the properties of gold
• Elements


  Substances that have specific chemical and physical properties and cannot be broken down into other substances through ordinary chemical reactions
• Atom


  The smallest unit of matter that retains all of the chemical properties of an element
• Elements with chemical symbols from English terms

  • C for carbon
  • Ca for calcium
• Matter


  Refers to anything that occupies space and has mass
• Four elements common to all living organisms

  • Oxygen (O)
  • Carbon (C)
  • Hydrogen (H)
  • Nitrogen (N)
• There are 118 elements, but only 92 occur naturally. The remaining elements have only been made in laboratories and are unstable
• All elements and the chemical reactions between them obey the same chemical and physical laws, regardless of whether they are a part of the living or nonliving world
• Hydrogen typically has one proton and one electron, but no neutrons
• Atom structure


  • Consists of an atomic nucleus containing protons and neutrons, and a cloud of electrons orbiting around the nucleus
• Most of the volume of an atom—greater than 99 percent—is actually empty space
• Number of electrons surrounding the nucleus


  Determines which kind of reactions the atom will undergo
• A single neutron or proton has a weight very close to 1 amu
• Electrons do greatly affect an atom’s charge, as each electron has a negative charge equal to the positive charge of a proton
• Electrons (negative charge) occupy a large, spherical cloud surrounding the nucleus
• Hydrogen (H) typically has one proton and one electron, but no neutrons
• Protons and neutrons do not have the same charge, but they do have approximately the same mass
• Scientists chose to define an alternative measure, the dalton or atomic mass unit (amu), to measure masses of protons and neutrons
• Negatively charged electron clouds of the atoms will repel each other if they get too close together, resulting in our perception of solidity
• Subatomic particles

  • Protons
  • Electrons
  • Neutrons
• Protons (positive charge) and neutrons (neutral charge) are found together in the tiny nucleus at the center of the atom
• Number of protons in the nucleus


  Determines which element an atom is
• In uncharged, neutral atoms, the number of electrons orbiting the nucleus is equal to the number of protons inside the nucleus, leading to an atom with no net charge
• Electrons are much smaller in mass than protons, only about 1/1800 of an atomic mass unit
• Atom of helium contains two protons, two neutrons, and two electrons