Chapter 14 Inside the Atom

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Chapter 14, 15, 16
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• Greek philosophers devised a theory of atoms, or
  tiny particles.
• John Dalton combined the idea of elements with
  the Greek theory of the atom.
• Matter is made up of atoms
• Atoms cannot be divided into smaller pieces
• All atoms of an element are made of different
  atoms
• Different elements are made of different atoms
• Daltons theory was tested by William Crookes and
  his cathode ray tube experiment

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• C. J.J. Thomson discovered negatively charged
  particles, electrons, which are part of every
  atom.
• 1. Thomson revised Daltons model to include a
  sphere with a positive charge and negatively
  charged electrons spread evenly within the
  positive charge
• 2. The negatively charged electrons and the
  positively charge in the sphere neutralize each
  other

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• D. Earnest Rutherford tested Thomsons model,
  which was found to be an inaccurate model of the
  atom.
• E. An atomic model with a nucleus was developed.
• 1. The positively charged proton is located in a
  very small space at the center of an atom
• 2. Most of an atom is empty space occupied by
  nearly mass less electrons.
• 3. Electrically neutral particles, neutrons, are
  also located in the nucleus.
• 4. The number of electrons equals the number of
  protons in an atom

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• F. The electron cloud model explains the
  unpredictable wave behavior of electrons, which
  could be anywhere in the area surrounding the
  nucleus.

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• Section 2 The Nucleus
• A. Atomic Number- number of protons in the
  nucleus of an atom
• 1. isotopes of an atom have the same number of
  protons but different number of neutrons. 2.
  Mass number is the number of neutrons plus the
  number of protons
• 3. Average atomic mass- the average mass of the
  mixture of an elements isotopes.
• 4. The strong nuclear force holds tightly
  packed protons together in a nucleus

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• B. Radioactive Decay occurs when an atom releases
  nuclear particles and energy.
• 1. When a proton is released, one element
  changes into another, a process called
  transmutation.

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• 2. Alpha Particle
• a. 2 protons and 2 neutrons, are released
  during transmutation
• b. Atomic number decreases

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• 3. Beta Particle
• a. A high energy electron from the nucleus is
  released with energy when an unstable neutron
  splits into an electron and a proton.
• b. Atomic number increases by one

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• C. Half-life of a radioactive isotope is the
  amount of time it takes for half of the sample
  to decay
• 1. Half lives range in length from fractions of
  a second to billions of years.
• 2. Carbon-14 dating is used to determine the age
  of artifacts and fossils.

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3. Radioactive waste must be disposed of
carefully to avoid harming people and the
environment
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• D. Synthetic elements are made in labs by
  smashing atomic particles into a target element.
• 1. Radioactive Isotopes from artificial
  transmutation are called tracer elements and can
  be used for medical purposes.
• 2. Tracer elements are also used to study the
  environmental impact of pesticides and
  fertilizers and to locate water resources.

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• Chapter 15
• Section 1 Introducing the Periodic Table
• By 1830 fifty-five different elements had been
  isolated and named.
• In 1869 Mendeleev arranged elements in order of
  increasing atomic mass and found that elements
  with similar properties fell into groups.
• Moseley improved the periodic table by arranging
  the elements according to atomic number instead
  of atomic mass

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• B. The modern periodic table contains seven
  periods or rows of elements whose properties
  change gradually and eighteen groups of columns,
  each with a family of elements having similar
  properties
• 1. Groups 1 and 2 along with groups 13 thru 18
  are called the representative elements.
• 2. Groups 3 and 12 are called the transition
  elements.

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• 3. A metal has luster, conducts heat and
  electricity, is malleable and ductile.
• 4. Nonmetals are usually gases or brittle solids
  at room temperature
• 5. A metalloid shares properties with metals and
  nonmetals
• 6. Symbols are abbreviation often base on the
  elements name.

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• Section 2 Representative Elements
• Groups 1 and 2 are active metals found in nature
  combined with other elements although hydrogen
  is placed in Group 1, it is not a metal and it
  shares properties with Groups 1 and 17
• Alkali metals- silvery solids with low densities
  and low melting points they increase in
  reactivity from top to bottom of the periodic
  table
• Alkaline earth metals- are denser, harder, have
  higher melting points, and are slightly less
  reactive than alkali metals in the same period.

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• B. Groups 13 through 18 may contain metals,
  nonmetal, or metalloids in solid, liquid, or gas
  form.
• 1. The Boron family elements in group 13 are all
  metals except boron, which is a metalloid these
  elements are used in a variety products.

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• The carbon group elements are all metalloids or
  metals, except for carbon itself.
• a. carbon is found in all living things and
  exists in several forms.
• b. Silicon and germanium are used in
  electronics as semiconductor
• c. Tin and lead are the two heaviest elements
  in Group 14

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• 3. The nitrogen group contains nitrogen and
  phosphorous, which are required by living things
  and which are used in industry
• 4. The oxygen family contains oxygen and sulfur,
  which are essential for life and used to
  manufacture many products.
• 5. The halogen groups elements form salts with
  sodium and with other alkali metals
• 6. The noble gases rarely combine with other
  elements they are often used in lighting and
  inflating balloons

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• Section 3 Transition elements
• Groups 3 to 12 are the transition elements most
  are combined with other elements in ores.
• The iron triad is composed of iron, cobalt, and
  nickel these metals have magnetic properties.
• Several transition elements can be used as
  catalysts, which are substances that make
  reactions occur faster without changing itself

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• B. The inner transition elements are called
  lanthanides and actinides.
• 1. The lanthanides are soft metals and were once
  thought to be rare.
• 2. All the actinides are radioactive several
  are synthetic elements that do not occur
  naturally.
• 3. Dental materials are sometimes made of new
  composites, resins, and porcelains.

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• Chapter 16
• Section 1 Why do atoms combine?
• The nucleus, containing protons and neutrons, is
  at the center of an atom and is surrounded by the
  electron cloud, an area of space around the
  nucleus where electrons travel.
• 1. Electrons have a negative charge and do not
  travel in well-defined orbits.
• 2. Each element has a different atomic structure
  consisting of a particular number of protons,
  neutrons and electrons

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• B. The number and arrangement of electrons in the
  electron cloud determines the physical and
  chemical properties of the element.
• 1. Electrons are arranged in different energy
  levels at different distances from the nucleus
• 2. The farther an energy level is from the
  nucleus, the more electrons it can hold.
• 3. Electrons in the level closest to the nucleus
  have the lowest amount of energy electrons
  farthest from the nucleus have highest amount of
  energy

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• C. Data from the periodic table can be used to
  understand energy levels.
• 1. The atomic number is the same as the number
  of protons in an electrically neutral atom
• 2. The number of electrons in an elements
  outermost energy level increases from left to
  right across a period.
• a. The first energy level is complete with two
  electrons, and the first period has two elements.
• b. The last element in each of the other
  periods has eight electrons in its outer energy
  level.

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• 3. Each column in the periodic table contains one
  element family or group with similar chemical
  properties.
• a. The noble gases in Group 18 do not combine
  easily with other elements because their energy
  levels are stable.
• b. The halogens have 7 electrons in their outer
  energy levels reactivity of the halogens
  decreases down the group.
• c. The alkali metals in Group 1 have one
  electron in their outer energy level reactivity
  of the alkali metals increases down the group

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• D. An electron dot diagram is the symbol for the
  element surrounded by as many dots as there are
  electrons in its outer energy level.
• 1. Dots are written on four sides of the element
  symbol.
• a. One dot represents a single electron
• b. Paired electrons are represented by two dots.

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• 2. A chemical bond is the force that holds two
  atoms together
• a. Electron dot diagrams can be used to show
  how atoms bond with eachother
• b. Atoms bond with other atoms so that each
  atom has a stable energy level

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• Section 2 How Elements Bond
• A. Atoms form bonds by losing electrons, by
  gaining electrons, by pooling electrons, or by
  sharing electrons.
• 1. An atom that is no longer neutral because it
  has lost or gained an electron is called an ion.
• 2. An ionic bond forms when positive and
  negative ions attract each other.
• a. Sodium Chloride is formed from sodium ions
  and chloride ions.
• b. Two or more elements that are chemically
  bonded form a compound.

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• 3. Some atoms can gain or lose more than one
  electron when they form ions.
• B. Metallic bonds form when metal atoms share
  their pooled electrons.

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• C. A covalent bond forms between atoms that share
  electrons.
• 1. Atoms sharing electrons form a neutral
  particle called a molecule
• a. Covalently bonded compounds are called
  molecular compounds.
• b. No electrons are involved in a double bond.

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