Chemical Bonds
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Chemical Bonds
What is this?Atom
The basic unit of matter.
Made of subatomic particles:
Protons: charge, mass?
Positive charge (+), mass = 1
Electrons: charge, mass?
Negative charge(-), mass = 0
Neutrons: charge, mass?
No charge (0), mass = 1
How do we know the number of electrons?The atomic number tells you the number of electrons.
What are electron shells?
They describe where electrons of different energy levels are located.
Why are electron shells important?
They determine how an atom behaves when in contact with another atom.
What is the periodic table?A map of the building blocks of matter.
Color in the non-metals in your periodic table.
How many valence electrons are in Fluorine (F) and Chlorine (Cl)?7 valence electronsHow many are needed to complete F and Cl?1 valence electron
How many valence electrons are in Lithium (Li) and Sodium (Na)?1 valence electronHow many do Li and Na need?7 valence electrons
If F or Cl bumps into Li or Na, what will happen? Make a prediction.
1) Identify the names of these atoms2) Are they metals or non-metals?3) What will happen when they meet?
1) Sodium and Chlorine2) Sodium is a metal and chlorine is a nonmetal3) ...
What is happening here?Chlorine (Cl) pulls the valence electron from sodium (Na). They become ions because they have a charge (an unequal # of protons and electrons).
They now both have complete valence shells.
What type of bond is this?An ionic bond: A chemical bond formed between two ions of opposite charges. Example: Sodium Chloride (NaCl)
So what will happen when a non-metal comes in contact with a metal?The nonmetal will pull the electron from the metal.Why does this happen?
Why does this happen? Nonmetals are more electronegative, which means they have a greater ability to pull electrons towards themselves.
Types of chemical bonds
Ionic Bonds:Between nonmetals and metals
Covalent Bonds:Between…?
Covalent Bonds● Occur when electrons
are shared between two atoms.
● Take place when bonds form between nonmetals and nonmetals. Why?
● Because they have similar electronegativity.
Number of Covalent BondsHow many electrons are shared in a single bond?2
In a double bond?4
In a triple bond?6
Bohr Model Structural Formula
Review: How do the nonmetals differ from the metals?
Nonmetals are more electronegative than metals.
They have a stronger pull on bonding electrons.
There are two types of covalent bonds: One in which electrons are shared equally and one in which electrons are shared but not equally. Which is which below?
Electrons shared between the 2 oxygens will be shared equally; Each oxygen will pull equally.
Oxygen is more electronegative than hydrogen. It will pull the electrons closer to itself. What will this do?
In a water molecule, paired electrons spend more time near oxygen, causing an unequal distribution of charge. There is a slight negative charge on the oxygen side of water and a slight positive charge on the hydrogen side.
The net charge is zero but there is a polarity (sides with different charges).
This is called a Polar Covalent Bond.
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Polar Covalent Bonds: Electrons are shared but not equally (e.g., always happens between an oxygen and a hydrogen)
Nonpolar Covalent Bonds: Electrons are shared equally (e.g., O2, oxygen). No difference in charge. Atoms in bond have the same or similar electronegativity.
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