Download atomic number on the periodic table

A Little Periodic Table History…
History of the Periodic Table
• Dmitri Mendeleev, a Russian
scientist born in Siberia in 1834, is
known as the father of the
periodic table of the elements
• The periodic table is designed
to help you predict chemical
and physical properties of
elements
Method Behind the Madness
• Mendeleev set out to find a pattern in the
elements
• He wrote facts on paper cards for each
element
 Melting Point
 Density
 Colors
 Atomic Masses
Method Behind the Madness (cont)
• After laying all of his cards out he noticed
that by arranging them according to their
properties they were arranged in order of
increasing atomic mass
• Mendeleev was even able to use the
patterns in his table to predict the properties
of undiscovered elements
• The first periodic table was published in 1869
The Genious of Mendeleev's Periodic Table - TedEd
Mendeleev Song
Today, elements are arranged in order of
increasing atomic number on the periodic table
Big
Science
Idea
Element Location
Elements are located in three main
categories on the periodic table based on
their physical properties
 Metals
 Nonmetals
 Metalloids
Physical Properties
Physical Property - a property
of matter that can be
observed or measured
WITHOUT CHANGING the
substance
Examples of Physical Properties
Mass – How much
matter is in an object
Malleable – Can be pounded/rolled
into a shape
Density – How tightly mass is
packed into an object
Color/Texture
Ductile – Can be stretched
into a long wire
Metals, Nonmetals, & Metalloids
Metals
Most elements are metals. The 88 elements to the
left of the stair-step line are metals or metal-like
elements.
Physical Properties of Metals:
 high luster (shininess)
 good conductors of heat
and electricity
 high density (heavy for their
size)
 high melting point
 ductile
 malleable
Metals
Non-Metals
Non-metals are found to the right of the stair-step
line. Their characteristics are opposite those of
metals.
Physical Properties of Nonmetals:
 no luster (dull appearance)
 poor conductor of heat and electricity
 brittle (breaks easily)
 not ductile
 not malleable
 low density
 low melting point
Non-Metals
Metalloids
Elements on both sides of the zigzag line have
properties of both metals and nonmetals.
These elements are called metalloids.
Physical Properties of Metalloids:
 solids
 can be shiny or dull
 ductile
 malleable
Antimony (Sb)
 conduct heat and electricity, but not as well as
metals
Metalloids
Scientists organize elements according
to their physical and chemical
properties
Big
Science
Idea
How to Read the Periodic Table
• The Periodic table is designed to help you predict
what an element's physical and chemical properties
are
• You can also predict what elements will bond with
each other
Elements are arranged:
Vertically into Groups
(also called Families)
Periodic Table Bitesize
(only show part 1)
Horizontally Into Periods
Periodic Table Arrangement
Groups or Families
• Vertical columns on
the periodic table
Periods
• Horizontal rows of
the periodic table
Why?
If you looked at one
atom of every element in
a group you would see…
Each atom has the same number of
valence electrons (the electrons in its
outermost shell).
Think back to the Bohr Model
An example…
The group 2 atoms all have 2 electrons in
their outer shells
Be (Beryllium) Atom
Mg (Magnesium) Atom
Valence Electrons
• Effect the way an atom bonds, which
determines many of the chemical properties
of the element
o Atoms can have anywhere between 1 and 8
valence electrons
• This is why elements within a group usually
have similar chemical properties
Chemical Properties
A chemical property is a
characteristic that is
observed when a
substance changes into
a different substance
Examples of Chemical Properties
Combustible – capable
of igniting at higher
temps
Corrosion
Reactivity
Oxidation – rusting or
tarnishing
Flammable –
capable of
igniting
Metals – Reactivity
Reactivity decreases from left to right
Metal Reactivity
Nonmetals – Reactivity
Reactivity increases from left to right
Not Reactive
If you looked at an atom from each
element in a period
you would see…
Each atom has the same number of
electron holding shells.
An example…
The period 4 atoms each have 4 electron
containing shells
4th Shell
K (Potassium)
Kr (Krypton)
Atom
Atom
Fe (Iron) Atom
Each group has distinct properties
The periodic Table is divided into several
groups based on the properties of different
atoms
For example…
The periodic table tells us
several things…
Periodic Table
Information on the periodic table:
•Atomic number
•Atomic symbol
•Mass number (Atomic Mass)
•Element name
•Group and period numbers
Think Inside the Box
Atomic Number: Number of protons
(also the number of electrons) in an
atom of an element.
Element’s Symbol:
An abbreviation for the element.
Element’s Name
Atomic Mass:
Number of protons + neutrons.
8
O
Oxygen
16
Chemical Symbols
• Shorthand way of representing the
elements
• Usually one or two letters
• Usually taken from the name of the
element
– Carbon-C, Calcium-Ca, Hydrogen-H, IodineI, Oxygen-O, Chlorine-Cl
Chemical Symbols
• Some symbols come from their Latin
name:
–
–
–
–
Gold-Au--aurum
Silver-Ag--argentum
Iron-Fe--Ferrum
Mercury-Hg--hydrogyrum
How do we know the number of
subatomic particles in an atom?
• Atomic number: this number indicates the
number of protons in an atom of a particular
element
– Ex: Hydrogen’s atomic number is 1
• So hydrogen has 1 proton
– Ex: Carbon’s atomic number is 6
• So carbon has 6 protons
**The number of protons is a unique property that
identifies an element.
Ex. 2 protons = He, 29 protons = Cu
Atomic Mass
• Atomic Mass Unit (amu) is used to measure
the particles in atoms
– Protons & Neutrons are about 1 amu
– Electrons are MUCH smaller
• It takes about 2,000 electrons to equal 1 amu
• Atomic Mass = Protons + Neutrons
Atomic #
Symbol
Mass #
Pick an element off the Periodic Table and
draw and label it just like this one!
Group and Period Numbers
Period Numbers
Group Numbers
How Can I Find Out the Number
of Protons and Electrons?
Atomic No. = # of protons
Since protons & electrons are
EQUAL...the atomic no. also tells
you the # of electrons
*Atomic # = # of Protons = # of electrons*
Let’s take a look:
A = Atomic number
P = Number of protons
E = Number of electrons
These are all the same number!!
So
Atomic # = # of Protons = # of electrons
Then How Can I Find Out the
Number of Neutrons?
Mass Number = number of protons +
number of neutrons
So
Neutrons = Mass Number – Atomic Number
Now let’s look at MAN:
M= Atomic Mass
-
A= Atomic Number
N= # of Neutrons
Simple math!
Mass minus atomic number gives you the
number of neutrons!!!
Let’s work a couple together
Let’s try Nitrogen!
Nitrogen
A= 7
P= 7
E= 7
M= 14
-A= 7
N= 7
Boron
A= 5
P= 5
E= 5
M= 11
-A= 5
N= 6
Now that we know how to
figure out protons, electrons,
and neutrons…
Let’s try to create a Bohr
Model
Lithium
Atomic Structure
Electrons = 3 (2 in the 1st shell, 1 in the 2nd shell)
+
3
Li
Lithium
7
+
Protons = 3
+
-
-
Neutrons = 4 (7-3 = 4)
Protons determine an element’s identity and
valence electrons determine its chemical
properties
Big
Science
Idea
SUMMARY
1. The Atomic Number of an atom = number of
protons in the nucleus.
2. The Atomic Mass of an atom = number of
Protons + Neutrons in the nucleus.
3.
The number of Protons = Number of Electrons.
4.
Electrons orbit the nucleus in shells.
5.
Each shell can only carry a set number of electrons.