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Science 5.3 2013-14
5.3 Notes
Question | Answer |
---|---|
Chemical bond formed when 2 atoms share electrons | covalent bond |
What kind of elements form covalent bonds? | non-metal and a non-metal |
What kind of elements form an ionic bond? | non-metal and a metal |
What is the most important characteristic to determine how an atom will bond? | the number of valence electrons |
What is the name for the group of atoms joined by covalent bonds? | molecule |
What is a double bond? | When atoms share two pairs of electrons |
How many electrons are shared in a double bond? | 4 |
Compared to ionic compounds, are the boiling and melting points higher or lower for molecular compounds? Why? | Lower because ionic bonds are much stronger than covalent bonds |
What is the greatest number of valence electrons an atom can have? | 8 |
What element has a full outermost shell with only 2 electrons? | Helium |
Why doesn't pure water conduct electricity? | It is covalently bonded so there are no ions to conduct the electricity |
What causes pairs of electrons to share unequally in covalent bonding? | The atom with more protons (so it's bigger!)pulls the electron closer to it and it becomes slightly negatively charged. The atoms are NOT ions. |
Name of a bond in which the electrons share unequally? | polar |
Name of a bond in which the electrons share equally? | nonpolar |
What is the shape of a molecule that contains polar bonds but is nonpolar overall? | straight line |
What is the shape of a molecule that contains polar bonds and is polar overall? | slightly bend,looks like Mickey Mouse ears! |
By sharing electrons, each atom becomes stable with how many electrons? Which element is the exception, and how many does it become stable with? Why? | 8, except H, which is 2 electrons b/c it's already stable so it doesn't need to share. |
What is a covalent bond? | the attractive force between each atom's nucleus for the shared pair of electrons |
What does "pair" mean? How many is a pair? | two |
Do atoms share one electron? | no |
How many covalent bonds can H form? Why? | one because it only needs one more electrons to have a full energy level |
What is a triple bond? | when atoms share three pairs of electrons |
How many electrons are shared in a triple bond? | 6 |
What is a molecular compound composed of? | molecules |
Describe characteristics of molecular compounds in regards to melting/boiling points and explain why. | lower melting points and boiling points compared to ionic compounds ionic bonds are much stronger than covalent bonds. Covalent bonds are weaker b/c they don't have a charge like ions do. |
Do molecular compounds conduct electricity? | no |
Explain surface tension of water in terms of polar covalent bonds. | b/c polar bonds have slight charges, each molecule is attracted to the surrounding molecules causing a tight skin across the surface of the water |
Why is there NO surface tension in a liquid containing nonpolar bonds? | b/c without the slight charge of polar bonds, there would be no electrical attraction b/t the molecules |