Quartz, salt, and sugar are all compounds that are solids. Their similarities and differences partly come from the way their atoms or ions are joined.
A compound is made of two or more elements that are chemically combined The forces that hold atoms or ions together in a compound are called chemical bonds. Chemical bonds are broken, and atoms are rearranged. New chemical bonds form water, a compound that has properties very different from the properties of the original gases.
Water s chemical formula tells us what atoms make up water, but it does not tell us anything about the way the atoms are connected A compound s chemical structure is the way the compound s atoms are bonded to make the compound. THINK: How can a blueprint tell you the structure of a building? Are all blueprints the same?
Two terms are used to specify the positions of atoms in relation to one another in a compound. Bond length is the distance between the nuclei of two bonded atoms When a compound has three or more atoms, a bond angle, the angle formed by two bonds to the same atom, tells which way these atoms point. THINK: What kind of model would be best for describing the structure of these compounds?
Structural formulas can also show the structures of compounds. THINK: What are the major differences between these two models?
A space-filling model shows the space that the oxygen and hydrogen atoms take up, or fill. A space-filling model also shows the relative size of atoms in a compound, but not the bond lengths.
Some chemical bonds are stronger than others THINK: What could better represent the bonds in a ball and stick model? Atoms can move back and forth a little, and their nuclei do not always stay the same distance apart this means bond lengths are actually averages. Bonds are not rigid, but they do hold atoms together tightly.
The chemical structure of a compound determines the properties of that compound. THINK of 5 real world examples of this concept Be ready to share them with the class!
Turn to page 180 Describe the structure of quartz Draw and label the chemical structure of quartz Use the internet to help you if you do not understand INVESTIGATE! ANSWER: How is the hardness of minerals explained by minerals chemical structure?
REVIEW: What is an ion? Table salt (sodium chloride) is found in the form of regularly shaped crystals. INVESTIGATE: What is the structure of these crystals? How does this give rise the structure of table salt? Is this attraction beneficial or not? Explain!!
Salt and sugar are both white solids that you can eat, but their structures are very different. INVESTIGATE: Draw and label the structures of both salt and sugar. How are they similar? How are they different?
INVESTIGATE: What do we breathe in all day, every day? Is it is compound or a mixture? What is it made of?
Turn to page 182 and read the two paragraphs Compare AND contrast each of the compounds in the table. Describe the bonds holding them together. Draw a model of each one! Use the internet if you need help!
Page 182 Questions 1-5 (please answer them in COMPLETE SENTENCES!!)
Atoms bond when their valence electrons interact Atoms join to form bonds so that each atom has a stable electron configuration There are two basic kinds of chemical bonding: ionic and covalent bonding The way that a compound bonds determines many of the properties of that compound
Atoms of metals, such as sodium and calcium, form positively charged ions. Atoms of nonmetals, such as chlorine and oxygen, form negatively charged ions Ionic bonds form from the attractions between such oppositely charged ions. Some atoms form bonds because they transfer electrons one gains, one loses.
Because sodium chloride is a network of ions, there is no such thing as a molecule of NaCl Read page 185 and describe the structure of sodium chloride. What are the ratios? Do all ionic compounds have the same ratio?
Electric current is moving charges. Solid ionic compounds do not conduct electric current because the charged ions are locked into place. But if you dissolve an ionic compound in water or melt it, it can conduct electric current. THINK: Why does this happen? What causes this to happen???
Compounds that are made of molecules, such as water and sugar, have covalent bonds. Atoms joined by covalent bonds share electrons Compounds that are networks of bonded atoms, such as silicon dioxide, are also covalently bonded. Covalent bonds usually form between nonmetal atoms
Covalent compounds can be solids, liquids, or gases Most covalent compounds that are made of molecules have low melting points- usually below 300 degrees c Molecules are free to move when the compound is dissolved or melted Most of these molecules do not conduct electricity because they are not charged
Nonpolar covalent bonds vs. polar covalent bonds What are these??? Read page 187 and make a comparison chart
Metals, such as copper, con conduct electricity when they are solid. Metals are also flexible, so they can bend and stretch without breaking. Copper, for example, can be pounded into thin sheets or drawn into very thin wire Metals are flexible and conduct electric current well because their atoms and electrons can move freely throughout a metal s packed structure
The atoms in metals such as copper form metallic bonds The attraction between an atom s nucleus and a neighboring atom s electrons packs the atoms together. This packing causes the outermost energy levels of the atoms to overlap electrons are free to move from atom to atom
But some compounds have both ionic and covalent bonds Such compounds are made of polyatomic ions, which are groups of covalently bonded atoms that have a positive or negative charge as a group A polyatomic ion acts as a single unit in a compound, just as ions that consist of a single atom do
Many compounds that you use either contain or are made from polyatomic ions Ex. Baking soda- sodium hydrogen carbonate, sodium carbonate, sodium hydroxide investigate how each of these polyatomic ions are used and what their chemical formula is. What other examples are listed in your book? What is one way you know a compound contains a polyatomic ion there s a super easy way to tell!
Many polyatomic ions contain oxygen Most of their names end in ite or ate What do these endings mean for the ions? Copy down the table in your book on page 190 you will see some of these on a quiz!!
Please complete questions 1-9 on page 190 in COMPLETE SENTENCES. Turn it into the basket when you are finished.
Ionic compounds are formed by strong attractions between oppositely charged particles. Cations(+) and anions(-) The names of ionic compounds consist of the names of the ions that make up the compounds
Cations form when they lose electrons how many electrons lost determines the ion s charge Anions form when they gain electrons how many electrons gained determines the ion s charge. Names will also change. Ionic compounds must have a neutral charge why??? How can this be accomplished???
Let s practice!!
Let s practice!!!
The word organic has many different meanings. Most people associate the word organic with living organisms In chemistry, the word organic is used to describe a type of compound.
An organic compound is a covalently bonded compound that contains carbon. Most organic compounds also contain hydrogen. Oxygen, nitrogen, sulfur, and phosphorus, can also be found in organic compounds.
When a compound is made of only carbon and hydrogen atoms, it is called a hydrocarbon Methane, CH4, is the simplest hydrocarbon Methane gas is formed when living matter, such as plants, decay, so it is often found in swamps and marshes. What do you think this bond looks like? Remember the special bonding of carbon molecules.
Alkanes are hydrocarbons that have only single covalent bonds. Methane is the simplest alkane but alkanes can also have C-C bonds THINK: What would the compound C2H6 look like? Draw it on your notes paper.
What do rubber, wood, plastic milk jugs, and the DNA in your cells have in common? A polymer is a molecule that is a long chain made of smaller molecules. Can you think of an example? I know ya can! Write at least 5 down that are not listed above.
Some polymers are natural, while others are artificial Rubber, wood, cotton, wool, starch, protein, and DNA are all polymers. polymers are usually plastics or fibers. What makes plastics special? How are they different than fibers?
The properties of a polymer are determined by its structure.aka Structure determines Function. Investigate the polymers of milk jugs, and rubber bands on page 201. Write down some helpful ways to remember polymers.
Biochemical compounds are organic compounds that can be made by living things. Biochemicals, which are essential to life, include carbohydrates, proteins, and DNA. THINK: What is the function of each of these biochemicals?
Biochemicals called Carbohydrates, which include sugars and starches, provide energy to living things. Investigate: What is table sugar made of? Pg. 202 THINK: What happens when you eat starchy foods? What must your body do?
Starch is made of only glucose Proteins, which provide structure and function to parts of cells, are much more pomplex. Proteins are made of many different molecules that are called amino acids The amino acids that make up a protein determine the protein s structure and function
All of your genes are made of DNA molecules DNA is a very long molecule made of carbon, hydrogen, oxygen, nitrogen, and phosphorus What is the shape of DNA? What are the monomers of DNA? What does the sequence of DNA determine?
Please complete questions 4 and 5 on page 204 Make sure you use COMPLETE SENTENCES! Turn it into the basket when you are finished