module 2

• Matter


  The substance of the material world. It constitutes anything you see or feel around you
• Types of matter


  • Organic matter (animals and plants)
  • Inorganic matter (materials and water)
• Physical properties of matter

  • Mass
  • Colour
  • Odour
  • Texture
  • Shape
  • Taste
  • Hardness
• Chemical element


  A pure form of matter consisting of entirely one type of atoms
• Compound


  A substance consisting of two or more different atoms in a fixed ratio
• Compounds have characteristics different from those of its elements
• Essential elements for life

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Calcium
  • Phosphorus
  • Potassium
  • Sulfur
• Trace elements are those required by an organism in much smaller quantities
• Adaptation to toxic elements

  • Some species can become adapted to environments containing toxic elements
  • For example, some plant communities are adapted to serpentine
• Atom


  The smallest unit of chemical element
• Subatomic particles


  • Neutrons (no electrical charge)
  • Protons (positive charge)
  • Electrons (negative charge)
• Atomic number


  The number of protons in the nucleus of an atom
• Mass number


  The sum of protons plus neutrons in the nucleus of an atom
• Isotopes


  Atoms of the same element that differ in number of neutrons
• Radioactive isotopes decay spontaneously, giving off particles and energy
• Energy levels


  The state of potential energy of an electron in an atom
• Valence electrons


  The electrons in the outermost shell of an atom
• Elements with a full valence shell are chemically inert
• Orbital


  The three-dimensional space where an electron is found 90% of the time
• Covalent bond


  The sharing of a pair of valence electrons by two atoms
• Types of covalent bonds

  • Single bond (sharing one pair of valence electrons)
  • Double bond (sharing two pairs of valence electrons)
• Structural formula


  The notation used to represent atoms and bonding
• Molecular formula


  An abbreviated representation of a covalent compound
• Electronegativity


  An atom's attraction for the electrons in a covalent bond
• Polar covalent bond


  A covalent bond where the atoms do not share the electron equally
• Ionic bond


  The attraction between a positively charged ion (cation) and a negatively charged ion (anion)
• Hydrogen bond


  The attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom
• Van der Waals interactions

  Attractions between molecules that are close together due to asymmetric electron distribution
• Atom


  The smallest particle of matter non-divisible by chemical means, composed of protons, neutrons and electrons
• Molecule


  The smallest part of a compound that still has the properties of that compound, formed when two or more atoms react or combine
• Types of inorganic molecules

  • Water
  • Acids
  • Bases
  • Salts
  • Gases
• Physical properties of water

  • Universal solvent
  • High specific heat and latent heat of vaporization
  • High degree of thermal conductivity
  • Immiscible with lipids
  • Neutral pH
  • Liquid at room temperature
  • High surface tension
• Physiological properties of water

  • Dissolve or hold in suspension materials of protoplasm
  • Furnish a medium for vital processes and substances
  • Moisten surfaces for gas diffusion
  • Regulate body temperature
  • Help in functions of sense organs
  • Serve as a lubricant and cushion
• Acid


  A substance that releases hydrogen ions (H+) in a water solution
• Properties of acids


  • Sour taste
  • Turn blue litmus paper to red
  • React with active metals to form hydrogen gas
• Base


  A substance that yields hydroxide ions (OH-) in a water solution
• Physiological Properties of Water

  • Dissolve or holds in suspension the materials of the protoplasm
  • Furnishes a medium for some vital processes and substances (nutrients, wastes, and hormones)
  • Moistens surfaces for gas diffusion
  • Regulates body temperature
  • Helps in the functions of the sense organs
  • Serves as a lubricant for movable surfaces
  • Serves as a cushion for the brain and spinal cord
• Acid


  Sour taste, turns blue litmus paper to red, reacts with active metals to form hydrogen gas
• Green mangoes are sour. The sour taste is due to the acid present in the fruit.
• Base


  Bitter taste, feel slippery, turn red litmus paper to blue, corrosive to the skin