Unit 2: Atoms Elements and Bonds Lesson 4: Ionic and Covalent Bonds

Bell Work What is an atom and what are the three parts of an atom and what are their charges? What is a chemical formula? What information can you get from a chemical formula? What are the two types of mixtures? What is the difference between a compound and a mixture?

Today’s Agenda Bell Work Review This week’s Agenda Ionic Bond Notes Review Questions

This Week’s Agenda Monday Tuesday Wednesday Thursday Friday Notes on Ionic Bonds Tuesday Notes on Covalent Bonds Wednesday Quizziz to Review Edpuzzle Finish Up notes Thursday Quiz on Ionic and Covalent Bond Review Worksheets Friday Mystery Friday (Depending on behavior)

SC Standards Standard 7.P.2: The student will demonstrate an understanding of the structure and properties of matter and that matter is conserved as it undergoes changes. 7.P.2.A Conceptual Understanding: All substances are composed of one or more elements. Elements are pure substances which contain only one kind of atom. The periodic table organizes these elements based on similar properties. Compounds are substances composed of two or more elements. Chemical formulas can be used to describe compounds. 7.P.2A.4: Construct explanations for how compounds are classified as ionic (metal bonded to nonmetal) or covalent (nonmetals bonded together) using chemical formulas. S.1A.6: Construct explanations of phenomena using (1) primary or secondary scientific evidence and models, (2) conclusions from scientific investigations, (3) predictions based on observations and measurements, or (4) data communicated in graphs, tables, or diagrams.

Today’s Objectives (SWBAT) Construct explanations of how compounds are classified as ionic or covalent using chemical formulas.

Day 1 Ions and Ionic Bonds

What are Ions? Ion Happens Metals tend to LOSE Nonmetals tend to GAIN Is an atom or group of atoms that had an electron change Happens When a neutral atom LOSES a valance electron The atom will become positive When a neutral atom GAINS a valance electron The atom will be negative Metals tend to LOSE Nonmetals tend to GAIN

Common Ions Ions that are made from more than 1 atom Some ions are made of several atoms Polyatomic ions Ions that are made from more than 1 atom Are positive or negative

Ionic Bonds Happens when atoms easily loose and electron and other gain an electron Valence electrons are transferred from one atom to another Example: Na will lose an electron and become positive Cl will gain an electron and become negative Ionic Compounds Made up of positive and negative ions Positive ions will equal negative ions

Example

Ionic Chemical Formulas A group of symbols that show the ratio of elements in a compound If no subscript assume the number is 1 Cl looses 1 valence electrons, thus it takes 2 to make it a neutral compound MgCl2 Magnesium will loose 2 electrons Lets us know that there are 2 Cl atoms

Brain Break (Answer the following questions) Take 5 minutes and answer these questions What is an ion? What are ionic bonds? What is a chemical formula?

Naming Ionic Bonds Name of the positive ion comes first The name of the negative ion come last

Properties of Ionic Compounds Form hard brittle crystals that have high melting points Conduct electricity when dissolved in water or melted Ionic crystals Form solids by building up repeating patterns of ions Crystals: orderly 3-D arrangement of ions Ions are attracted to ion of an opposite charge High Melting Point Take a lot of energy to break apart ion crystals Melting point of NaCl is 801C

Day 1 Review Questions An atom that loses a valance electron become a (positive/negative) ion. An atom that gains a valance electron becomes a (positive/negative) ion Determine the number of atoms of each element in the chemical formula Na2S Ionic bonds are strong enough to cause almost all compounds to be ______________ at room temperature.

Day 2 Covalent Bonds

Bell Work What are ions? How do they form What are ionic bonds? Name 3 common ionic bonds

Covalent Bonds Molecule Form between nonmetals Share electrons Electron Sharing Attraction between shared electrons Proton in nucleus of each atom hold the atoms together Molecule A neutral group of atoms joins by covalent bonds

Covalent Bonds Carbon has 4 valence electrons (Remember what group Carbon is in) Carbon can have 4 bonds Hydrogen has 1 valence electron (remember what group Hydrogen is in) It can only form 1 bond Carbon and Hydrogen will share an electron

How Many Bonds Draw an electron dot diagram Count number of valence electrons Examples H=1 valence electron=1 bond C=4 valence electrons=4 bonds O=6 valence electrons=2 bonds Double Bonds 2 atoms share 2 pairs of electrons Triple Bonds 2 atoms share 3 pairs of electrons

Different Bond Example

Brain Break (Take 5 minutes to answer these questions) What is a covalent bond? How is it different then an ionic bond? How many bonds can you have in a covalent bond?

Properties of Molecular Compounds Compounds made of molecules Contains atoms that are covalently bonded together Do not conduct electricity when melted or dissolved in water. Have lower melting and boiling points Do not contain charged particles Weaker bonds then ionic Table sugar melts at 190C table salt melts at 801C

Partially Charged Atoms of some elements have more pull then others Unequal sharing of electrons causes covalently bonded atoms to have slight electric charges

Nonpolar and Polar Bonds Each atom pulls on the electron the same Electron are shared equally Polar Bonds When one atom have a slightly stronger pull on the electrons The strong atom will be slightly negative The weaker atom will be slightly positive

Van der Waals Forces Van der Waals Forces Weak attraction between the slightly positive and negative charges Higher melting and boiling point Example Water

Day 2 Review Draw an electron dot diagram for 1 iodine atoms Water is an example of a(n) (ionic/molecular) compound. When do molecular compounds form? Sodium chloride is an example of a(n) (ionic/molecular) compound. Ionic compounds form when…