Download Chapter 10 Power Point - Biloxi Public Schools

Chapter 10
Atoms & Periodic Table
10-1 The Structure of Atoms
Chemical symbols - an abbreviated way to write the name
of the element.
The first letter is capitalized; the second (if present) is
lowercase.
Latin names are used for many elements so the letters
are not always the English initials.
Common Symbols:
C = Carbon
H = Hydrogen
O = Oxygen
N = Nitrogen
Na =
W =
Fe =
Au =
Sodium
Tungsten
Iron
Gold
Atoms - smallest particle of an element; the
basic building blocks of matter.
The Parts of an Atom:
Nucleus - positively charged center that
contains protons and neutrons:
the protons have a positive charge: p+
the neutrons have a neutral charge: no charge
Electron cloud - surrounds the nucleus and
contains electrons which are negative: e-
Descriptive numbers
Atomic number = the number of protons
in the nucleus (whole #) and always the
same for that element.
Mass number = the number of protons
PLUS neutrons in the nucleus (whole
number); average atomic mass rounded
to the nearest WHOLE number.
the # of p+ always equals the # of ein an atom.
Relative masses of sub-atomic
particles (as compared to each other)
amu = atomic mass unit
Proton’s mass = 1 amu
Neutron’s mass = 1 amu
Electron’s mass = 0.00054348 amu
The mass of an e- is actually 1 / 1840
of the mass of a proton or a neutron.
Atomic Models
Atomic Models - used to describe atoms
because atoms are so very microscopic.
Bohr model - electrons move in definite orbits
around the nucleus.
Electron cloud model - e- move in regions
around the nucleus in “energy levels”. This
model is most widely accepted.
Relative size of electron and nucleus
If the electron cloud were the size of a
pro football stadium, the nucleus would
be the size of a golf ball..
Ex: the nucleus: golf ball, the e-cloud: stadium
10- 2 The Electron Cloud
The electron cloud is NOT the exact location of each electron,
just the probable location or area where it moves.
The electrons move around the nucleus in “energy levels”.
The electrons in the energy levels closer to the nucleus have
less energy than the electrons that are farther from the
nucleus.
Energy levels (n) have a maximum number of e- they can hold.
1st level can hold 2 e2nd level up to 8 e3rd level up to 18 e4th level up to 32 e-
use the 2(n)² formula
10-2 Smaller Particles of Matter
Quarks - are the smaller particles of matter that make up
protons and neutrons.
*One arrangement of 3 types of quarks forms a neutron.
*Another arrangement of 3 different quarks forms a
proton.
A supercollider is used to accelerate protons in order to
study collisions that can help reveal information about
the inner structure of the atom.
Masses of Atoms
Atomic mass - the relative mass of an atom; based upon an
atomic mass unit; compared to carbon-12.
Atomic mass unit is 1/12 the mass of a carbon-12 atom.
Mass number - the sum of the protons & neutrons in an
atom.
10-3 Masses of Atoms
Isotopes - atoms of the same element with different
numbers of neutrons (same # of protons); less
common than the main element. The existence of
isotopes accounts for the average atomic mass.
Average atomic mass - the average mass of the
mixture of an element & its isotopes; only a whole
number if radioactive or man-made; usually
carried to 2 or 3 places past the decimal.
The # of protons determines what the element is;
the # of neutrons determines the isotope of that
element.
10-4 The Periodic Table
The Periodic Table - arrangement of elements according to
repeated changes in properties.
Dimitri Mendeleev (Russian, 1800's) arranged all the
elements known at that time, in order of increasing
atomic masses & discovered a repeating pattern of
properties or characteristics.
***There were some gaps in masses so he placed
question marks in their spots. Later, elements were
discovered to fill in these gaps. His predictions about
elements, their masses & properties proved to be
true.***
Henry Moseley arranged the elements by increasing
atomic number. This is the form of periodic table that
we use today.
The Periodic Table
Groups or Families of Elements
Groups or Families of Elements - the vertical columns on
the table, numbers 1 thru 18
Elements in the same group/family have similar properties
such as the # of electrons in their outer shell or energy level.
Electron dot diagrams were developed using the symbol
and “dots” to represent the electrons in the outer energy
level. (see pg 260.)
Each group or “vertical” column has a specific number of
e- in the outer shell. The last column has eight.
Periods are the “horizontal” rows. Each row indicates the
number of “energy levels” or shells in the atom.
Groups of elements
Metals – located on the left side of the chart; most
are solids, are shiny & good conductors of heat
& electricity.
Transition elements – located in groups 3 thru 12;
have metallic properties.
Metalloids - have properties of metals &
nonmetals; found along the zig-zag line or the
“staircase” of the chart.
Non-metals – located on the right side of chart;
usually gases or brittle solids; not good
conductors.
All make up work due by Friday,
December 11th
Daily Work, Quizzes,
and Tests
Element Symbol Quiz #4 is
Thursday, December 10th
Ch. 9 and 10 Test is Friday