cognito #1-25 vids

• Everything, whether living or non-living, is made up of tiny particles called atoms
• A single cell probably contains more than 100 trillion atoms
• Atom


  Made up of multiple smaller particles
• Structure of an atom

  • Central nucleus
  • Electrons orbiting in shells
• The nucleus is made up of protons and neutrons
• Nucleus


  • Made up of protons
  • Made up of neutrons
  • Packed together in a tight ball
• Protons


  Have a relative mass of one and a positive charge
• Neutrons


  Have a relative mass of one and no charge (neutral)
• Electrons


  Have a mass 2000 times smaller than protons/neutrons and a negative charge
• Protons and neutrons have the same mass
• Electrons are comparatively tiny
• Protons are positive and have a one plus charge
• Neutrons have no charge and are neutral
• Electrons have a negative charge which is the same size as the positive charge of the proton
• Atoms have a radius of around 0.1 nanometers
• Most of an atom is actually empty space
• The nucleus is 10,000 times smaller than the width of the atom


  Electrons are even smaller
• In a neutral atom, the number of protons equals the number of electrons
• Ion


  An atom that has lost or gained electrons
• A negative ion has more electrons than protons
• A positive ion has more protons than electrons
• The periodic table represents different types of atoms called elements
• Elemental symbol


  A one or two letter symbol that represents an element
• Oxygen is represented by the symbol O and lithium by the symbol Li
• Atomic number


  Tells us how many protons the atoms of that element have
• The number of protons in an atom determines which element that atom is
• Mass number


  Tells us the total number of neutrons and protons in an atom
• The number of neutrons can be found by subtracting the atomic number from the mass number
• The atomic number also tells us how many electrons the atom has
• An atom is made up of a central nucleus which comprises protons and neutrons and has electrons orbiting that nucleus
• Protons


  Subatomic particles that determine the element
• Electrons


  Subatomic particles that orbit the nucleus
• The smallest element is hydrogen as its atoms have just one proton in their nucleus with one electron orbiting it
• Nuclear symbols


  Boxes in the periodic table representing different elements
• Atomic number


  The number in the bottom left of the nuclear symbol, unique to that element, representing the number of protons
• Element symbols


  One or two letter symbols that represent the element name
• Isotopes


  Different forms of the same element that have the same number of protons but a different number of neutrons
• The most common form of carbon is carbon-12, which has six protons, six neutrons, and six electrons
• A rare form of carbon is carbon-13, which has six protons, seven neutrons, and six electrons
• Carbon-13 has a mass number of 13 rather than 12