Pure Substances 4/2

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Groups of atoms that are bonded together are called molecules. More specifically, molecules are made up of atoms that are held together by chemical bonds. When atoms come together to form molecules, it is a chemical change. A chemical change occurs when a substance combines with another to form a new substance. This process is also called chemical synthesis. In contrast, a physical change are changes affecting the form of a chemical substance, but not its chemical composition. Pure substances are defined as substances that are made of only one type of atom or only one type of molecule. They are samples of matter that have definite chemical and physical properties. You may have seen examples of pure substances on the periodic table. If you didn't already know, the periodic table is a table of the chemical elements arranged in order of atomic number, usually in rows, so that elements with similar atomic structure appear in vertical columns. The pure substances that are present on the periodic table are called elements. Elements are pure substances containing only one kind of atom, that cannot be separated in any physical or chemical means. They can't be chemically inter converted or broken down into simpler substances and are primary constituents of matter. Another pure substance is called a compound. A compound is a pure substance containing two or more kinds of atoms. Compounds are two or more different elements joined by chemical bonds. Compounds can't be separated. These bonds form as a result of the sharing or exchange of electrons among the atoms. In addition, another pure substance is called a mixture. A mixture occurs when two or more pure substances are not chemically combined. This means that they can be separated by physical means. 

S&EP - SP7: Engaging in argument from evidence

I used evidence to defend my explanation. I answered and filled out a packet of worksheets about elements, compounds, and mixtures, providing the notes that I took in my notebook based off of the slideshow that my teacher put together as evidence. I formulated evidence based on solid data when I stated that elements, compounds, and mixtures are all made up of pure substances, using the fact that elements are pure substances containing only one type of atom, compounds are pure substances containing two or more types of elements that are chemically bonded, and mixtures are when two or more pure substances are together but not chemically combined, as evidence. I examined my own understanding in light of the evidence. I used to think that compounds and mixtures weren't made up of pure substances, but because of the slideshow presentation that my teacher showed my class and I, now I think that compounds and mixtures are definitely made up of two or more pure substances. I collaborated with my peers in searching for the best explanation. I did some research on elements, compounds, and mixtures which I discussed with my class and classmates at my table. Together we figured out that the basic details of the composition of elements, compounds, and mixtures.

XCC: Patterns

As I filled in the packet of worksheets about elements, compounds, and mixtures, I noticed a pattern. I used this pattern to help me fill out a certain activity in the packet, where I had to label if the different listed objects were elements, compounds, mixtures, or none of the above. The pattern that I found to help me identify what pure substance combination each object was, was a pattern in each of the object's formula. For example, the chemical formula of elements is distinctive because it should only contain a single capitol letter. I knew that an object was a mixture when it contained two or more capitol letters in its chemical formula. For instance, I know that a diamond is an element because its formula is C. Even though a diamond element isn't listed on the periodic table, it is made up of only one type of atom which is carbon. As well as I know that something is a compound if its chemical formula contains two or more capitol letters. I know that sugar in particular is a compound because its formula, C6H12O6, contains more than one capitol letter.