Transcript Ch 7 Powerpoint

Ch 7 Notes
Atoms
‘building blocks’
Element
‘one kind of atom’
Shown w/
Symbols
Molecule
two or more atoms
bonded together,
atoms can be the
same or different
Compounds
‘different kinds
of atoms’
Shown w/
Formulas
Subatomic Particles
& Their Charges
• protons = positive
• electrons = negative
• neutrons = neutral
Practice – indicate the # of P+,
E-, & No for each element:
Na, Al, K, Fe
Valence Electrons
• # of electrons found in the
outermost energy level
• determines how the element
reacts chemically
• What are the # of electrons in the
1st four energy levels?
• Which group of elements are NOT
reactive b/c their outer energy
level is full?
What is Chemical Bonding?
• Combining atoms of two or
more different elements
• Forms a new substance
• Determined by the # of
valence electrons
• What are the types of
bonds?
Ionic Bonding
• Electrons are given up or
received
• Opposite charges attract
• The positive atom (cation)
bonds with the negative atom
(anion)
Types of Ions
Cation (+) & Anion (-)
Ionic Bonding
• Atom X has few valence
electrons & tends to lose those
electrons – this creates a
positive charge
• Atom Z has many valence
electrons & tends to gain more
electrons to fill its outer shell –
this creates a negative charge
Ionic Bonding of Na & Cl
The more electrons to move, the
more energy required.
The
Crystal
Lattice
Arrangement
of ions is
specific to that
compound
Created by
ionic bonds
Identifying Bonds
1.Two nonmetal atoms usually
form covalent bonds.
2.A metal and a nonmetal atom
usually form ionic bonds.
Covalent Bonding
• Electrons are shared between
atoms
• These shared electrons fill up the
valence shell of each atom
• Elements that exist in nature as
two atoms of the same element
covalently bonded are called
DIATOMIC elements
Covalent
Bonding
of Water
Covalent Bonding
creating C2H6
Electron Dot Diagram
Electron Dot Diagram
Polyatomic Ions
• a group of covalently bonded
atoms that act like a single
atom when combining with
other atoms
• usually form ionic bonds
• Copy the charts of common
polyatomic ions on page 186
Metallic Bonding
• metallic solids are solids made
of entirely one metal element
• bonds are formed between
two or more metal atoms
• the outer electrons that are
easily given up form a
common electron cloud
Oxidation Number
• the # of electrons an atom
gains, loses, or shares when it
forms chemical bonds
• Example: Na (+1) & Cl (-1)
• CH4 … C(+4) & H (-1)
• the sum of oxidation numbers
of the atoms must equal zero