Compounds, Chemical Formulas and covalent bonds
Compounds, Chemical Formulas and covalent bonds P.274 Lesson 2
Atomic Structure
•P.269 • Atoms made up of: – Protons – Neutrons – Electrons
Valence electrons • Definition: – A valence electron is an outermost electron that participates in chemical bonding.
Electron dot diagrams
Electron dot diagrams
Electron dot diagrams
Electron dot diagrams
Noble gases • He, Ne, Ar • What makes noble gases different to the other elements on the periodic table? – Stable – Doesn’t bond naturally, because.... – They don’t need to gain or lose electrons
Compounds • How/why do puzzle pieces fit together?
Compounds • Definitions: 1. Element: A substance made up of one type of atom. 2. Compound: A substance that is made up of 2 more elements that have been chemically combined.
Covalent Bonding • Definition: A chemical bond formed when 2 atoms share 1 or 2 or 3 pairs of valence electrons • The atoms then form a stable covalent compound
Single Covalent Bonding
Double Covalent Bonding
Triple Covalent Bonding
Covalent Bonding • Which is stronger, the single covalent bond between H2, or the triple covalent bond between N2? • Why?
Molecules • Definition: Group of atoms held together by covalent bonding that acts as an independent unit. • For Example: – Sugar – C12H22O11
Molecules • What are some of the properties of covalently bonded compounds (molecules)? – Low melting and boiling points (they’re usually in GAS or LIQUID phase) – Poor conductors of thermal energy – Poor conductors of electricity
Polar Molecules • What does POLAR mean? – Opposites; opposite ends; like the poles of the earth; or like the poles of a magnet (North & South
• Definition of a POLAR MOLECULE: – A molecule that has a partial positive end and a partial negative end, because of unequal sharing of electrons
Polar Molecules
Non-polar Molecules
Chemical Formula • Definition: – Group of chemical symbols and numbers that represent the elements and numbers of atoms of each element that make up the compound
• It is like a recipe; shows all ingredients and how much of each ingredient; like a cake
Chemical Formula • CO2 :
– 1 X carbon atom – 2 X oxygen atoms
• H2O:
– 2 X hydrogen atoms – 1 X oxygen atom
• CH4: –?
Atomic Structure
•P.269 • Atoms made up of: – Protons – Neutrons – Electrons
Valence electrons • Definition: – A valence electron is an outermost electron that participates in chemical bonding.
Electron dot diagrams
Electron dot diagrams
Electron dot diagrams
Electron dot diagrams
Noble gases • He, Ne, Ar • What makes noble gases different to the other elements on the periodic table? – Stable – Doesn’t bond naturally, because.... – They don’t need to gain or lose electrons
Compounds • How/why do puzzle pieces fit together?
Compounds • Definitions: 1. Element: A substance made up of one type of atom. 2. Compound: A substance that is made up of 2 more elements that have been chemically combined.
Covalent Bonding • Definition: A chemical bond formed when 2 atoms share 1 or 2 or 3 pairs of valence electrons • The atoms then form a stable covalent compound
Single Covalent Bonding
Double Covalent Bonding
Triple Covalent Bonding
Covalent Bonding • Which is stronger, the single covalent bond between H2, or the triple covalent bond between N2? • Why?
Molecules • Definition: Group of atoms held together by covalent bonding that acts as an independent unit. • For Example: – Sugar – C12H22O11
Molecules • What are some of the properties of covalently bonded compounds (molecules)? – Low melting and boiling points (they’re usually in GAS or LIQUID phase) – Poor conductors of thermal energy – Poor conductors of electricity
Polar Molecules • What does POLAR mean? – Opposites; opposite ends; like the poles of the earth; or like the poles of a magnet (North & South
• Definition of a POLAR MOLECULE: – A molecule that has a partial positive end and a partial negative end, because of unequal sharing of electrons
Polar Molecules
Non-polar Molecules
Chemical Formula • Definition: – Group of chemical symbols and numbers that represent the elements and numbers of atoms of each element that make up the compound
• It is like a recipe; shows all ingredients and how much of each ingredient; like a cake
Chemical Formula • CO2 :
– 1 X carbon atom – 2 X oxygen atoms
• H2O:
– 2 X hydrogen atoms – 1 X oxygen atom
• CH4: –?
