BUILDING ATOMS
REVIEW ATOMIC CONCEPTS BUILD MODELS OF ATOMS AS A REVIEW BUILD MODELS OF IONIC BONDING BUILD MODELS OF COVALENT BONDING BUILD MODELS OF HYDROGEN BONDS COMPARE & CONTRAST IONIC, COVALENT AND HYDROGEN BONDING OBJECTIVES
BUILD A HELIUM ATOM Draw the helium atom & label its parts
Jot down the following What would happen if the number of protons changed? What would happen if the number of electrons changed? What would happen if the number of neutrons changed?
BUILD A HYDROGEN ATOM Draw the hydrogen atom & label its parts What happens if you change the number of: Protons? Electrons? Neutrons?
ORBITALS
BUILD ATOMS CNOFCNOF
ELECTRONEGATIVITY "Electronegativity is the power of an atom when in a molecule to attract electrons to itself." Increases left to right Decreases top to bottom
QUESTIONS How many electrons fit on each orbital? How does the proton number compare to the electron number? How does the number of electrons in the outer orbital relate to the stability of the element? Which elements are the most stable? Why? Which elements are the most reactive? Why?
QUESTIONS How many electrons fit on each orbital? 2 on the inner s orbital Eight on the next two
QUESTIONS How does the proton number compare to the electron number? They are the same if the element is unchanged/unaltered
QUESTIONS How does the number of electrons in the outer orbital relate to the stability of the element? Elements with full orbitals or valence shells are more stable & less reactive Elements with partially complete valence shells are more reactive The closer an element is to having a completely full or completely empty valence shell is more reactive
QUESTIONS Which elements are the most stable? Why? Nobel gases (Column VIII) Their outer orbitals are filled
QUESTIONS Which elements are the most reactive? Why? The halogens (VII) Their outer shell is almost complete Metals (I) Their outer shell is almost empty (need to lose one electron)
BUILD A FLUORINE ATOM & A HYDROGEN ATOM HOW WILL THE GAIN/LOSS OF AN ELECTRON CHANGE THE STABILITY OF EACH? WHAT HAPPENS WHEN AN ELECTRON IS MOVED FROM HYDROGEN TO FLUORINE? MOVE THE ELECTRONS DRAW A BEFORE AND AFTER DIAGRAM OF THE HF MOLECULE
BUILD IONIC COMPOUNDS LiCl MgO BeS NaF
IONIC BONDING Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the non-metal accepts those electrons to become a negatively charged anion. Ionic bonds require an electron donor, metal, and an electron acceptor, nonmetal.
QUESTIONS In the models you built, which atoms are the cations? Which are the anions? Which elements of the periodic table tend to become negative ions/anions (have the greatest potential for gaining electrons)? Why? Which elements of the periodic table tend to become positive ions/cations (have the weakest ability to retain their electrons)? Why? Which columns would combine well in order for both to be more stable?
QUESTIONS Which elements of the periodic table tend to make ionic bonds? How does electronegativity correlate with ionic bonding? Why don’t all the elements of the periodic table form ionic bonds? What do atoms that cannot form ionic bonds do to become more stable?
QUESTIONS In the models you built, which atoms are the cations? Which are the anions? Cations – Li, Mg, Be, Na Anions – Cl, O, S, F
QUESTIONS Which elements of the periodic table tend to become negative ions/anions (have the greatest potential for gaining electrons)? Why? Column VII (halogens) Only missing one electron & have high electronegativity
QUESTIONS Which elements of the periodic table tend to become positive ions/cations (have the weakest ability to retain their electrons)? Why? Far left, column I They have only one electron in their outer orbital & have low electronegativity
QUESTIONS Which columns would combine well in order for both to be more stable? Columns I & VII Columns 2 & VI
QUESTIONS Which elements of the periodic table tend to make ionic bonds? Columns I & VII Columns II & VI
QUESTIONS How does electronegativity correlate with ionic bonding? Atoms with high electronegativity steal electrons Atoms with low electronegativity have their electrons stolen
QUESTIONS Why don’t all the elements of the periodic table form ionic bonds? Elements are unable to steal or give enough electrons Electronegativity too low to steal enough electrons Electronegativity too high to release enough electrons
QUESTIONS What do atoms that cannot form ionic bonds do to become more stable? They share
BUILDING COVALENT MOLECULES Make two hydrogen atoms Are these atoms likely to form ionic bonds? NO – have equal electronegativity & cannot give or take What can these atoms do to become stable? Form covalent bonds
BUILD COVALENT MOLECULES H2H2
CH 4 NH 3
BUILD COVALENT MOLECULES O 2 CO 2
COVALENT BONDING Electrons are shared – valence shells then complete
BUILD COVALENT MOLECULES C2H6C3H8C2H6C3H8
C2H6C3H8C2H6C3H8
C 2 H 6 (ethane) C 3 H 8 (propane)
QUESTIONS How do the valence electrons influence molecular bonding? How does electronegativity influence molecular bonding?
QUESTIONS How do the valence electrons influence molecular bonding? The number of open places on the valence shell determine the number of bonds the atom can form
QUESTIONS How does electronegativity influence molecular bonding? If the difference in electronegativity between the 2 atoms is great, then ionic bonds form (one atom steals the atoms from another) If the electronegativity is equal (or close), then covalent bonds form
HYDROGEN BONDING - DRAW CH 4 C 2 H 6 C 3 H 8
HYDROGEN BONDING - DRAW O 2 CO 2
HYDROGEN BONDS How many bonds can the following atoms make: H? O? C?
HYDROGEN BONDING - DRAW H 2 O H 2 O 2 CH 2 F CH 4
QUESTIONS Which molecules are symmetrical? Which are polar and which are non-polar? How does symmetry correlate with polarity? How does electronegativity correlate with polarity?
QUESTIONS Which molecules are symmetrical? H 2, O 2, CH 4
QUESTIONS Which are polar and which are non-polar? Polar - H 2 O & CH 2 F Non-polar - H 2, O 2, CH 4
QUESTIONS How does symmetry correlate with polarity? Symmetrical molecules are non-polar Asymmetrical molecules are polar
QUESTIONS How does electronegativity correlate with polarity? The atom in the molecule with the higher electronegativity will pull the electrons to it unequally This creates an unequal distribution of charge (without becoming a charged ion)
HYDROGEN BONDING Bonds that forms between the positive and negative ends of a water molecule (hydrogen to oxygen)