Chemistry Chapter 5

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Chemistry Chapter 5
2015-01-11 13:20:21

Chemistry cue cards
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  1. Atom
    The smallest particle of an element that retains the identity of the element
  2. Dalton's Model of The Atom
    • All matter is made up of small particles called atoms (true)
    • Compounds are created when atoms of different elements link together in definite proportions (true)
    • Atoms can no longer be created, destroyed or divided into smaller particles (no longer true)
    • All atoms of the same element are identical in mass and size. The atoms of one element are different in mass and size from other elements (not quite true)
    • Atoms are small, hard, indestructible spheres that is the smallest particle of an element (not true)
  3. Thomson
    • Discovered the electron in 1897
    • He inferred that because an atom contains negative particles it must contain positive particles
    • He created the raisin bun model
  4. Rutherford
    • Constructed to gold foil experiment¬†
    • A beam of positively charged particles (alpha particles) was shot through gold foil
    • Rutherford expected the beam to go straight through the foil but some of the particles rebounded. He inferred that there must be a small dense ball of positively charged particles in the center of the atom, electrons are separated from it
    • Thus discovering the nucleus
    • He created the planetary model
  5. Energy Levels
    • Electrons can only move within fixed regions (energy levels)
    • To move up energy levels and electron must absorb enough energy (quantum)
    • The row in which the element is in tells you how many energy levels it has with electrons in it
  6. Filling Valence Energy Level
    • During chemical reactions one atom can join with another by gaining, loosing or sharing valence electrons
    • Having a full set of valence electrons provides chemical stability
  7. Electron
    • Negative particle
    • Relative mass of 1
    • Travels in energy levels
    • The number of electrons in the valence level (last energy level) determines how many bonds the atom can make
    • Not confined to the nucleus so they can move from one atom to another
  8. Subatomic Particle
    • Particles that make up an atom
    • The number of electrons and protons are the same so the atoms are neutral
    • Protons, neutrons, electrons
  9. Nucleus
    The center of an atom
  10. Proton
    • Positive particle
    • Relative mass of 1836
    • Located inside the nucleus
    • Number of protons determines what the atom is (what element)
  11. Neutron
    • Neutral particle
    • Relative mass of 1837
    • Located inside the nucleus
    • The number of neutrons = the mass number-the atomic number
  12. Atomic Number
    The number of protons in the nucleus and the number of electrons in a neutral atom
  13. Mass Number
    The number of protons + the number of neutrons
  14. Isotope
    • Atoms of an element that have the same number of protons but a different number of neutrons
    • Each isotope has a unique mass number so they specify each isotope by placing its mass number after the name of the element
    • Eg. C-12, C-14
  15. Bohr-Rutherford Diagram
    • Used to show the arrangement of subatomic particles for an element
    • Protons and neutrons are placed in a center circle (the nucleus)
    • Electrons are placed surrounding the nucleus in energy levels (1st energy level has two electrons, 2nd energy level has eight electrons, 3rd energy level has eight electrons)
  16. Ions
    • The atom that results when an atom gains or looses electrons
    • The elements are the same because the protons didn't change
    • Electrons are gained, lost or shared to look like the nearest noble gas
    • It is shown by drawing the normal B-R diagram with an arrow (showing the amount of electrons gained/lost) pointing to the new B-R diagram showing what the atom looks like now surrounded by square brackets with either a positive or negative sign in the top right corner depending on the charge of the atom
  17. Atomic Mass
    • Average size of naturally occurring isotopes
    • Mendeleev organized them in the periodic table
  18. Periodic Table
    • Organizes elements based on increasing atomic masses
    • Ion charge is included because some elements can gain or lose electrons making them positively or negatively charged
    • Position of an element helps to predict the physical and chemical properties
    • Classified as metals, non-metals and metalloids
  19. Metal
    • Left side of the table
    • Properties: solid, shiny, good conductor, malleable,
  20. Non-Metal
    • Right side of the table
    • Properties: some gas, some liquid, not shiny, poor conductors, brittle
  21. Metalloid
    Shares properties with both metals and non-metals
  22. Period
    • Horizontal row
    • Numbered 1-7
  23. Group
    • Vertical column
    • Numbered 1-18
    • Can also be called a family because elements in groups often have similar properties
  24. Alkali Metal
    • Group number 1
    • Low melting point
    • Malleable
    • Highly reactive (close to noble gas)
  25. Alkaline Earth Metals
    • Group number 2
    • Highly reactive
    • Less reactive than group number 1
    • Heated=burn in air
    • Produce bright, colourful flames (used in fireworks)
  26. Halogens
    • Group number 17
    • Non-metals
    • Highly reactive/corrosive
    • As you go from F-->At the melting points increase
    • F and Cl are liquids
    • I is a liquid
    • At is a solid
  27. Noble Gasses
    • Group number 18
    • Colourless at room temperature
    • Non-reactive
    • Used in energy efficient light bulbs
  28. Valence Electrons
    • Electrons in the outermost level of an atom
    • Arrangement of valence electrons determine the properties of the element
    • Atoms in the same group have the same number of valence electrons
  29. Reactivity and Atom Size
    • The distance between the outermost electrons and the nucleus determines the size of the atom
    • As you go down a group the elements have more energy levels so the valence electrons are farther away causing a larger atom
    • The farther away valence electrons are the easier they are to loose because the attraction between the nucleus and electrons is less causing a higher reactivity
    • Atoms get larger as you move from right to left in a period
    • All valence electrons occupy the same amount of energy levels so change in size comes from decreased attraction between the valence electrons and the nucleus
    • This causes increase in reactivity of metals across a period going from right to left