Chapter 3 Atoms and the Periodic Table

1
Chapter 3 Atoms and the Periodic Table

• What are atoms?
• Tiny units that determine the properties of all
  matter
• What does atom mean in Greek?
• Unable to be divided

2
What is the atomic mass?

• The mass of an atom based on the average mass of
  isotopes of the element
• The mass of the protons the neutrons in the
  nucleus of the element
• example 6
• C
• 12
• has an atomic mass of 12

3
What is the atomic number of an atom?

• The number of protons in the nucleus
• The number of protons gives the atom its identity
• 6
• C
• 12 Has 6 protons

4
What is a nucleus?

• The central portion of an atom, containing both
  neutrons and protons

5
What is a neutron and where is it located?

• The neutral particle found in the nucleus of an
  atom which has a mass about equal to a proton
• Determined by subtracting the number of protons
  from the mass number of the element
• Example 8
• O
• 16 neutrons 16-8 8

6
What is a proton?

• Positively charged particle in the nucleus of an
  atom
• Atomic number of an element gives an element its
  identity
• Example 7
• N
• 14 has 7 protons

7
What is an electron and where is it located

• The negatively charged particle in the electron
  cloud of an atom
• Equal to the atomic number of a neutral element
  and the atomic number minus the charge for an
  elemental ion
• Example 6 6
• C C4
• 12 has 6 12 has 6-42

8
What are valence electrons?

• outer most energy
• level electrons

9
Information represented for an element

• 8
• atomic number (protons)
• O
• element symbol
• 15.99
• atomic mass

10
What is electron affinity?

• The attraction of an atom for an additional
  electron
• Metals have low affinity because they give away
  electrons
• Nonmetals have high affinity because they take on
  electrons
• The electron affinity tends to increase from left
  to right in the periodic table and from bottom to
  top

11
What are families/groups?

• Elements grouped together by common properties.
  They fall in the same vertical column of the
  periodic table
• Column 1alkali metals (1 oxidation )
• Column 2 alkaline earth metals(2 oxid )
• Column 3-12 transition metals (many have
  multiple oxidation number-least reactive of the
  metals)
• Column 16 chalcogens (-2 oxidation )
• Column 17 halogens (-1 oxidation ) most
  reactive nonmetals
• Column 18 noble gases (0 oxidation )
  nonreactive due to filled outer energy level
• lanthanide series
• actinide series

12
Where is the period in the periodic table?

• Horizontal rows in the periodic table
• Each represents an energy level

13
What are metals?

• Groups of elements that has
• Luster (shiny)
• Good conductors of heat and electricity
• 1-3 valence electrons
• Located in the periodic table left of the
  metalloids excluding H
• Solids are room temperature(ex mercury)

14
What are metalloids?

• Elements that have properties of both metals and
  nonmetals.
• Located diagonally between the metals, nonmetals
• B, Si, Ge, As, Sb, Te, At

15
What are nonmetals?

• Elements that do not have properties of metals
• Located on the right side of the periodic table
• Have more than 4 valence electrons
• Dull/lack luster
• Do not conduct heat or electricity well
• Typically gases or brittle solids at room
  temperature

16
What is a subscript?

• Small lowered number after the symbol for an
  element that indicates the number of atoms of the
  element present in the formula of the molecule
• Subscripts of one in a symbol are understood and
  therefore not shown
• Example O2 or NaCl or K2SO4

17
What is ionization energy

• Energy needed to remove an electron from an atom.
• Ionization energy tends to increase from left to
  right and decrease from top to bottom

18
Periodic trends of Elements

• Reactivity of metals increases down the periodic
  table and from right to left across the periodic
  table
• Reactivity of non metals increases up the
  periodic table and from left to right across the
  periodic table
• Atomic radius increases down the periodic table
  and form right to left across the periodic table