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Periodic Table
Ionic Bonds
Covalent Bonds, Molecular Bonds, and polar bonds
Metallic Bonds and bonding in Metals
Valence electrons and oxidation number
100
What does the periodic table give you?
The periodic table gives you information about the arrangement of electrons in atoms. Recall that the periodic table is organized by atomic number (number of protons in the nucleus of an atom)
100
How do ions form?
An ion is an atom or group of atoms that has an electric charge. When an atom loses an electron, it loses a negative charge and becomes a positive ion. When an atom gains an electron, it gains a negative charge and becomes a negative ion. Ions that are made of more than one atom are called polyatomic.
100
What is a covalent bond and what is the force that holds the atoms together?
A covalent bonds the chemical bond formed when two atoms share electrons (Example H20). The force that holds atoms together in a covalent bond is the attraction of each atom;s nucleus for the shared pair of electrons.
100
What is an alloy?
An alloy is a mixture made of two or more elements that has the properties of metal. In every alloy at least one characteristic is metal.
100
What are valence electrons and how do they relate to dot-diagrams?
Valence electrons are those electrons that have the highest energy level and are held most loosely. Each element has a specific number of valence electrons ranging from 1 to 8. An electron dot diagram includes the symbol of an element surrounded by dots (representing the valence electrons). Each dot stands for one valence electron.
200
Compare periods and groups.
As the atomic number increases on the periodic table, the number of electrons also increases. A period ends when the highest energy level has 8 electrons. Valence electrons in the next period are higher energy level. This repeating pattern means that the elements within a proud, or column, always have the same number of valence electrons. The elements within a group have similar properties because they all have the same number of valence electrons in their atoms.
200
What is an ionic bond and how do they form?
Since oppositely charged particles attract, the positive ion and the negative ion attract each other. An ionic bond is the attraction between two oppositely charged ions. Ionic bonds form as a result of the attraction between positive and negative ions. A compound that consist of positive and negative ions is called an ionic compound.
200
Compare double bonds and triple bonds.
When two atoms share two pairs of electrons is a double bond. A triple bond in which their atoms share three pairs of electrons.
200
Explain why iron is almost always used as an alloy?
Alloys are generally stronger and less likely to react with air or water than are the pure metals from which they are made. Iron is an extremely strong metal and good for making tools. However iron objects rust when exposed to air and water. For this reason iron is often used as an alloy to make steel. Steel tools are nearly as strong as iron but resist rust much better.
200
Explain how atoms can react.
Atoms usually react in a way that makes each atom more stable. One of two things may happen: Either the number of valence electrons increases to eight, or the atom gives up loosely held valence electrons. Atoms that react this way can become chemically combined.
300
What is a group?
A group is a row in the periodic table. It can be called a family as well.
300
What is a chemical formula and how do you name ions?
A chemical formula is a combination of symbols that shows the ratio of elements in a compound. When ionic compounds form, the ions come together in a way that the compound reflects this balance. For an ionic compound, the name of the positive ion comes first, followed by the name of the negative ion.
300
What is a molecular compound and how do they compare to ionic?
A molecular compound is a compound that is composed of molecules. The molecules of a molecular compound contain atoms that are covalently bonded. Compared to ionic compounds, molecular compound generally have lower melting points and boiling points, and they do not conduct electricity when dissolved in water.
300
What is a metallic bond and how does it relate to an alloy?
Each metal ion is held in the crystal by a metallic bond which is an attraction between a positive metal ion and the electrons surrounding it. A metal or metal alloy consist of positively charged metal ions embedded in a "sea" of valence electrons.
300
How do valence electrons and oxidation number relate?
Valence electrons are the number of electrons on the outermost ring. This number is used to determine the oxidation number, which is the number of electrons likely to be given away or received in a chemical bond.
400
What is a period?
The row in the periodic table is known as a period.
400
What are the properties of an ionic compound?
In general ionic compounds are hard, brittle crystals that have high melting points. When dissolved in water or melted, the conduct electricity.
400
What is the difference between polar and non polar bonds?
A covalent bond in which electrons are shared unequally is called a polar bond. If both atoms pull equally on the electrons, neither atom becomes charged. A covalent bond in which electrons are shared equally is a nonpolar bond
400
What does the "sea" of electrons model explain?
The "sea of electrons" model of solid metals explains the ease with which they can change shape, their ability to conduct electric current, their luster, and their ability to conduct heat.
500
Why do the elements within a group have similar properties to?
The elements within a group have similar properties because they all have the same number of valence electrons in their atom.
500
Compare covalent and ionic bonding.
Ionic bonds form as a result of the attraction between positive and negative ions. For example Na+ and Cl- attract each other. The chemical bond formed when two atoms share electrons in a covalent bond. Covalent bods usually form between atoms of nonmetals. In contrast, ionic bonds usually form when a metal combines with a nonmetal.
500
How does a covalent bond relate to a tug-a-war game?
Atoms of some elements pull more strongly on shared electrons than do atoms of other elements. As a result, the electrons are pulled more toward one atom, causing the bonded atoms to have slight electrical charges.
500
Why can metals be stretched and shaped?
Most metals are flexible and can be reshaped easily. Metals act this way because the positive ions are attracted to the loose electrons all around them rather than to other metal ions. These ions can be made to change position however, the metallic binds between the ion and the surrounding electrons keep the metals from breaking.