8th Chapter 3- Atoms and Bonding

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Chapter 3
Atoms and Bonding
Lesson 1
Atoms, Bonding, and the
Periodic Table
Atom
The smallest particle that
can still be considered
an element and the
building blocks of all
matter.
3
The Structure of Atoms
All atoms have the same structure. Atoms consist of
protons, neutrons, and electrons. An atom’s nucleus
contains tightly packed protons and neutrons.
Protons: Positive charge (+1)
Neutrons: No Charge
Electrons: Negative Charge (-1)
A neutral atom has the same number of protons and
electrons and a charge of zero.
4
Element
A substance that can not be
broken down into any other
substance by physical or
chemical means.
Any single element is made of
only one type of atom.
5
Valence Electrons
Electrons of an atom are found in different energy levels.
Electrons at higher energy levels = higher energy.
Valence Electrons: electrons with the highest
energy. They are the electrons involved
in chemical bonding.
The number of valence electrons an element has
determines the chemical properties of that element.
6
Electron Dot Diagrams
Also known as Lewis Dot Structures.
Each element has a different number of valence
electrons. Elements can have from 1 to 8 valence
electrons.
Electron dot diagrams show how many valence
electrons an atom has. They include an
element’s chemical symbol and dots that
represent the element’s valence electrons.
7
Chemical Bond
The force of attraction that
holds atoms together as a
result of the
rearrangement of
electrons between them.
8
The Periodic Table
The periodic table gives you information about the valence
electrons in an element.
The periodic table is organized by rows called periods and
columns called groups.
Each element has an atomic number which tells you how
many protons each atom of the element has.
9
10
Lesson 2
Ionic Bonds
How do Ions Form?
Ions: atom or group of atoms with an electric charge.
When a neutral atom loses a valence electron it loses a
negative charge. It becomes a positive ion. When a neutral
atom gains an electron it gains a negative charge. It
becomes a negative ion.
Metal atoms are more likely to lose electrons. Nonmetal
atoms are more likely to gain electrons.
12
Common Ions
◂
◂
◂
◂
◂
◂
◂
◂
Hydroxide Ion (OH-)
Peroxide Ion (O22- )
Sufate Ion(SO32- )
Nitrate Ion(NO3-)
Nitrite (NO2-)
Phosphate Ion (PO43-)
Acetate Ion (C2H3O2-)
Ammonium Ion (NH4+)
13
Ionic Bond
The attraction between two oppositely charged ions.
The resulting compound is called a ionic compound. Ionic
compounds are made of positive and negative ions.
In an ionic compound the total positive charge of all the
positive ions equals the total negative charge of the
negative ions.
Polyatomic Ions: made of more than one atom.
14
How are Formulas and Ionic
Compounds Written?
15
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