Transcript Periodic Table & Elements

Elements, Isotopes, Ions &
the Periodic Table
Standard Atomic Notation
Ex: Carbon :
Atomic Number (Z=6)
Atomic Mass 12.01 - 12 amu
(round to the nearest whole number)
For any atom the atomic number is
equal to the number of protons and
electrons.
 All atoms MUST BE electrically neutral.
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Question: Find the number of protons (p+),
neutrons (no), and electrons (e-).
The Periodic Table
Periodic Law – “when elements are
arranged in order of increasing atomic
mass, chemical and physical properties
form patterns that repeat at regular
intervals.”
Mendeleyev’s Periodic Table
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In 1872, Mendeleyev organized a
periodic table; he listed all elements
known at the time using the periodic law.
Mendeleyev left some blank spaces
where known elements did not appear to
fit. He suggested that elements would be
discovered that would fit into these gaps.
He was right.
The Modern Periodic Table
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Family or Group – elements with similar
chemical or physical properties are lined
up in vertical columns.
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Period – periods are the horizontal rows
of elements and the properties of these
elements change from metallic to nonmetallic as we move from left to right.
Most periodic tables include:
the English name for each element
 international symbol
 atomic number
 atomic mass *
 physical state at SATP
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* Atomic Mass – is defined relative to a carbon atom,
which has a mass of 12 atomic mass units. Therefore
an atomic mass unit (amu) is 1/12 of the mass of a
carbon atom.
**SATP (standard ambient temperature and pressure)
– is a set of conditions established by IUPAC to
promote consistency when discussing properties of
various substances. SATP refers to a temperature of
25 oC and a pressure of 100 kPa (kilopascals)
STP (standard temperature and pressure) – may also
be used from time to time and is defined as 0 oC and
101.325 kPa.
The Stair Case
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The modern periodic table is divided by
“the staircase line” which separates
metals from non-metals.
Elements
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All elements on the periodic table are
represented by a symbol.
 These symbols are either observed as a single
capital letter or a capital letter followed by
lower case letters.
 Although there are many languages in the
world and various elements have different
names with respect to each language, the
symbols on the periodic table are universal.
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Who decides which symbols and
names will be used?
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A group of scientists belonging to the
International Union of Pure and Applied
Chemistry or IUPAC specify the rules for
chemical names and symbols.
What does the Periodic Table Tell
Us??
Names of Groups and Series of
Elements
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Group 1 metals are known as alkali metals
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Group 2 metals are known as alkaline-earth metals
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all form oxide coatings (rust) in oxygen Ex: MgO, CaO
Group 17 elements are known as halogens
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soft, silver colored metals
all react violently with water
extremely reactive (Fluorine the most reactive)
Group 18 elements are known as noble gases
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extremely unreactive
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Groups 1, 2 and 13-18 are known as the representative elements
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best follow the periodic law
Groups 3-12 are known as the transition elements or transition
metals
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exhibit a wide array of chemical and physical properties
do not follow the periodic law as closely as the representative
elements
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Lanthanides – (rare-earth elements) from atomic number 58-71
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Actinides – from atomic number 90 to 103
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Transuranic elements – all elements beyond uranium (atomic
number 92)
Isotopes
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We know that all atoms of the same
elements are not completely identical.
Some have different masses. This is
caused by an increase in the number of
neutrons of an element. Atoms that have
the same number of protons but different
number of neutrons are called isotopes:
Ex: carbon-12 & carbon-14
Ions
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When atoms gain or lose electrons to fill their shells
they turn into ions. Ions are atoms or groups of atoms
that have a positive or negative charge.
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Cations - Have a positive charge
 Anions - Have a negative charge
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When atom changes into an ion it drops the last three
letters of its’ name and changes them to
-ide
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Charges of ions are relative to the periodic
table.
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Halogens (17 or VIIA) - all make anions with a
charge of -1
Group 16 or VIA - All make anions with a charge of
-2
Group 15 or VA - All make anions with a charge of 3
Alkali Metals (1 or IA) - All make cations with a
charge of +1
Alkali Earth Metals (2 or IIA) - All make cations with
a charge of + 2
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Transition metals (3-12) can have
multiple charges. All make cations, but
they can make different charges. These
ions can be found on the periodic table.
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Ex: Fe