Mt 2 Chemical Bonds

But first, let’s review What do we call the smallest form of an element? What does the Atomic Number of an element tell us? How do we determine the number of electrons found on the outer ring? What is the name of electrons that are found on the outer ring? How do we determine the number of electron rings an element has?

How is the structure of an atom related to bonding? The keys to answering that question is related to the Number of Valence Electrons Number of Electron Rings

How is the structure of an atom related to bonding? Valence Electrons – the number of electrons that are in the outer ring of an atom Electron Rings/orbitals – the number of rings or orbitals an atom has that can hold electrons

What is an atom? An atom is the smallest form of matter Has an equal number of protons & electrons

What is an ion? An ion is an atom that has either lost or gained electrons Negative Ion: Gained Electrons Positive Ion: Lost Electrons

What is an ion? Metals will lose electrons Electrons lost is equal to number of Valence electrons Example: Lithium 1 Valence Electron, Loses 1 electron Nonmetals will gain electrons Electrons gained will equal the number of electrons needed to equal 8 Example: Oxygen 6 Valence Electrons, Gains 2 electrons

Why do atoms want to form a Chemical Bond? They want to become more STABLE which means they want to be at a lower energy state All Atoms want to have a FULL OUTER RING The only elements that have a full outer shell are the Nobel Gases Therefore, all elements want to look like Noble Gases, meaning they want their electron rings to be filled Neon Atom Nobel Gas Lithium Atom

What do we call the product of a bond? Atoms will form a Molecule or Compound when they bond

What is the Octet Rule? When atoms form bonds, they follow the Octet Rule Octet Rule atoms tend to gain, lose or share electrons so as to have 8 electrons

C would like to N would like to O would like to Gain 4 electrons Gain 3 electrons Gain 2 electrons

What are the rules of electron shells? The 1st shell can hold up to 2 electrons, and each shell thereafter can hold up to 8 electrons. Keep in mind that there are subshells that can also hold differing amounts of electrons.

What are the types of chemical bonds? Ionic Bonds Covalent Bonds Metallic Bonds

What is an Ionic Bond?

What is an Ionic Bond? Examples Types of Elements Electron Activity: A bond formed between a metal and a nonmetal that have become ions Electron Activity: Electrons are transferred from the metal to the nonmetal Examples NaCl, CaCl2, K2O

Review - What is an ion? An ion is an atom that has either lost or gained electrons Metals lose electrons to form Positive Ions number of electrons are less than the number of protons Nonmetals gain electrons to form Negative Ions Number of electrons are more than the number of protons

What is a Covalent Bond?

What is a Covalent Bond? Types of Elements Electron Activity A bond formed between Non-metals Electron Activity Electrons are SHARED between the nonmetals They do not conduct electricity or heat at any state (solid, liquid, gas) Examples; O2, CO2, C2H6, H2O, SiC

Example: Covalent Bond F2

Covalent Bonds

What is a Metallic Bond?

What is a Metallic Bond? Types of Elements in bond Electron Activity “Sea of Electrons” surround the positive charges within the metal atom Holds metal atoms together very strongly Good conductors at all states, lustrous, very high melting points Form Alloys – a mixture of metals Examples of alloys: Brass (copper + zinc), Bronze (copper + tin)

Finds Gold And Drowns in a Sea of Electrons What is a Metallic Bond? Finds Gold And Drowns in a Sea of Electrons

A Sea of Electrons

Review What elements form an Ionic Bond? What elements form a Covalent Bond? What elements form a Metallic Bond? What is the electron activity (what are the electrons doing) in each bond?