Download Unit 2/B: Chemical Interactions

Unit 2/B: Chemical Interactions
Chapter 5: Atomic Structure and the
Periodic Table
Chapter 6: Chemical Bonds and
Compounds
Chapter 7: Chemical Reactions
Chapter 8: Solutions
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Chapter 5: Atomic Structure and
the Periodic Table
A substance’s atomic structure
determines its physical and chemical
properties
5.1 Atoms are the smallest form of elements
5.2 Elements make up the periodic table
5.3 The periodic table is a map of the elements
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
5.1 Atoms are the smallest form
of elements
Before, you learned:
•All matter is made of atoms
•Elements are the simplest substances
Now, you will learn:
•Where atoms are found and how they are
named
•About the structure of atoms
•How ions are formed from atoms
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
All matter is made of atoms
• Substances vary - How many different
substances can there be?
• 2400 years ago – Greek philosophers thought
there were four basic substances – air, water,
fire, and earth
• Today – chemists know of about 100 basic
substances, call elements, that account for
everything we see and touch
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Atoms in Earth’s Crust and Living Things
Aluminum
8% Iron
Other 5%
12%
Earth's Crust (top 100 km)
Oxygen
47%
Silicon
28%
Nitrogen
Hydrogen 3%
10%
Carbon
23%
Humans
3%
Oxygen
61%
Atoms of the element
hydrogen account for about
90% of the total mass of the
universe
Hydrogen makes up only
about 1% of the Earth’s crust
– mostly in the form of water
% by mass
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Names and Symbols of Elements
• Name Origin Examples:
–
–
–
–
Magnesium from the region in Greece, Magnesia
Lithium from Greek word lithos, “stone”
Neptunium named after planet Neptune
Einsteinium and Fermium named after scientists Albert Einstein
and Enrico Fermi
• Elements have a name and symbol
–
–
–
–
–
–
–
–
Hydrogen: H
Sulfer: S
Carbon: C
Aluminum: Al
Cadmium: Cd
Lead: Pb
Iron: Fe
Gold: Au (from aurum,
Goldandin
Atomic Structure
theLatin)
Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Each element is made of a different
atom
• Early 1800’s: British scientist John Dalton:
– each element is made of tiny particles called
atoms
– All atoms of a particular element are identical, but
are different from atoms of all other elements
• Ex: the atoms of silver are different from an atoms of
iron
– Atoms cannot be divided into anything simpler
• Not exactly true…
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
The Structure of an Atom
• Atoms contain charged particles – either positive or negative
– Positives repel positives
– Negatives repel negatives
– Positive and negative attract
• Atoms – three types of particles:
– Protons – positively charged
– Neutron – uncharged
– Electron – negatively charged
• Protons and neutrons are
– found in the nucleus of an atom
– Are of similar mass
• Electrons
– move around the outside of the nucleus
– Have a much smaller mass than protons or neutrons
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
The Structure of an Atoms
• Atoms are about 10-10m in diameter!
– Millions of atoms are in the period at the end of a
sentence
– The electron cloud is actually 10,000 times the
diameter of the nucleus!
• But…electrons are bout 2000 times smaller than the protons
or neutrons
• Can never determine the exact location of an electron –
always moving around
• Negative attraction to the positive keeps electrons close to
the nucleus, but away from each other
– No electrical charge if # protons = # electrons
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Atomic Numbers and Mass Numbers
• All atoms are composed of the same particles…
– Different numbers of protons in the nucleus
• Atomic number = # protons in the nucleus
• Atomic mass number = # protons + # neutrons
– Same elements have same # protons but not always the
same # neutrons, so may have different atomic masses
– Ex: Chlorine atoms have 17 protons, some have 18
neutrons, some have 20 neutrons = Chlorine isotopes
– Isotopes: atoms of the same element that have a
different number of neutrons
• Chlorine-35, Chlorine-37
– # protons? # neutrons?
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Atoms form ions
• If # protons = # electrons  no electrical
charge
• Ion: formed when an atom loses or gains one
or more electrons
– What if an atoms loses a proton?
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Formation of Positive Ions
•
•
•
If the atoms loses one electron, the charges are no longer balanced: one more
proton than electrons
Size is different: fewer electrons, less repulsion
Lose one electron: X+, lose two electrons: X2+
Ex: Na+, Ca2+
Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties
Formation of Negative Ions
•
•
•
If the atoms gain one electron, the charges are no longer balanced: one less
proton than electrons
Size is different: more electrons, more repulsion
Gain one electron: X-, gain two electrons: X2Ex: Cl-, O2Atomic Structure and the Periodic Table - A
substance’s atomic structure determines its
physical and chemical properties