Exam 4 Flashcards
Chapters 15-end
What is it called when atoms bond together through their electrons?
Bond formation
What are valence electrons?
Electrons in the outermost shell of an atom. These are the ones that participate in chemical bonding.
True or false: According to the older system of grouping on the periodic table, the group number equals the number of valence electrons in an atom
true
What is the electron-dot structure?
A notation showing the valence electrons surrounding the atomic symbol.
What are the three types of bonds?
ionic (metal and non-metal), metallic (two metals), and covalent (two non-metals)
What is an Ion?
an atom that has lost or gained one or more electrons
What is a cation?
an atom that has a positive charge because it has lost electrons.
What is an anion?
an atom that has a negative charge because it has gained electrons.
What are ionic compounds?
bonds formed between a metal and a non-metal, held together by the attraction between cations and anions.
True or false: Ionic compounds must have a net charge of zero
true
Give the formula and name of the ionic compound formed by each pair of elements:
K+ and Cl-
KCl - Potassium Chloride
Give the formula and name of the ionic compound formed by each pair of elements:
Mg+2 and O-2
MgO - Magnesium Oxide
Give the formula and name of the ionic compound formed by each pair of elements: Mg+2 and F-1
MgF2 - Magnesium Flouride
Give the formula and name of the ionic compound formed by each pair of elements: Na+ and S-2
Na2S - Sodium Sulfide
Describe Metallic Compound
outer electrons in metal atoms are held only weakly by the nucleus. This weak attraction allows the electrons to move about quite freely.
What are covalent Bonds?
the type of electrical attraction in which atoms are held together by their mutual attraction for shared electrons.
True or false: multiple covalent bonds are possible
True, the number of covalent bonds an atom can have equals its number of unpaired valence electrons
What are polar covalent bonds?
Bonding electrons shared unequally between two atoms. Partial charges on atoms.
Electrons within a covalent bond are shared evenly when the two atoms are the same. H:H
They may be shared unevenly when the bonded atoms are different. H :F
What are non-polar covalent bonds?
bonding electrons shared equally between two atoms. No charges on atoms.
What are ionic bonds?
Complete transfer of one or more valence electrons. Full charges on resulting ions.
True or false: Water is non-polar
false, water is VERY polar
What are the four effects of polarity in water?
- Water has an unusually high boiling point compared to other molecules of comparable size.
- Water dissolves other polar substances
- Water dissolves many ionic substances
- Water does not dissolve non-polar substances
Explain Solubility
“Like dissolves like”
Polar compounds dissolve polar (or ionic) compounds; non-polar compounds dissolve non-polar compounds.
What are the five unusual properties of water?
- High specific heat capacity
- High heat of vaporization
- Ice is less dense than liquid water
- Dissolves a wide range of polar and ionic substances
- Has a higher than expected boiling point
What is a pure substance? Give three examples
A material consisting of only one type of element or compound
Au, NaCl, H
What is a mixture?
A collection of two or more pure substances that can be separated by physical mechanics