Elements and Compounds

Transcription

1 Elements and Compounds

2 Essential Questions: 1. How are atoms arranged in the 3 states of matter? 2. What is an element? 3. What is the difference between elements and compounds? 4. What are valence electrons?

3 Elements and Compounds Matter Is everything around you Anything that has mass and takes up space Can be found in 3 main states (forms) solid, liquid, or gas

4 Elements and Compounds Solid Phase of Matter Has a definite volume and definite shape Molecules are tightly packed and vibrate in place. Form a definite structured pattern *strong Does not flow particles cannot move/slide past one another

5 Elements and Compounds Liquid Phase of Matter Has a definite volume but no definite shape It always takes the shape of the container Flows easily - particles can move past one another

6 Elements and Compounds Gas Phase of Matter Has no definite shape or definite volume Lots of free space between particles Particles can move very fast past one another Takes the shape and volume of its container.

7 Elements and Compounds Pure Substance Has a definite composition Can be either an element or a compound The composition of a pure substance doesn t vary - - it s always the same Molecule H2 Element H Compound H2O

8 Elements and Compounds Element Is a pure substance that cannot be broken down into any other substance. It is represented on the periodic table by a chemical symbol. Ex: Au is Gold Au Au Au

9 Elements and Compounds Compound A chemical substance that is formed when two or more different elements chemically bond in a specific proportion. The elements lose their individual chemical properties and the compound has new properties. It is represented by a chemical formula. Ex: NaCl - Sodium Chloride (salt) C 6 H 12 O 6 (glucose) Explosive solid Poisonous gas Now we have table salt - - which is safe to eat!

10 Elements and Compounds Counting elements in a molecule Count the number of different capital letters or element symbols in the compound.

11 Quick Action Elements and Compounds 1. Get with your table and draw this chart on your table with Expo marker. Discuss how to count the number of different elements in a compound. Formula H 2 O NaCl # of different elements Name of elements 2. Complete the chart by counting the elements and naming them. C 6 H 12 O 6 NaOH

12 Elements and Compounds Mixture A combination of many different elements Not chemically combined Can be easily separated Ex: Trail mix or a salad

13 Check for Understanding Can you Differentiate between elements, compounds, and mixtures?

14 Molecules

15 Essential Questions: 1. What are the basic differences of elements, molecules, and compounds? 2. What determines the number of molecules in a chemical formula?

16 Molecules Lets Review The basic building blocks for all matter is an atom. An element is a substance consisting of a single type of atom.

17 Molecules Compounds are Chemical bonds that are a result of the sharing or exchanging (gain or lose) electrons on the last energy level (called valence electrons) among the atoms. 2 Hydrogen atoms 1 Oxygen atom Water Molecule

18 Molecules Molecules are A group of atoms bonded together Made up of two or more atoms The atoms can be the same or different. Examples of molecules O 2 oxygen O 3 - ozone molecule H 2 O water CO 2 - carbon dioxide H 2 SO 4 sulfuric acid

19 Molecules Molecules are formed as a result of the sharing or exchange of valence electrons among atoms. The goal of bonding is to create happy atoms - - this means they have a full outer electron shell. J 6 valence electrons in an oxygen atom Oxygen atoms Needs 2 electrons to have a full outer shell Oxygen molecule O 2 Valence electrons are always looking to fill the outer most electron layer. By sharing electrons both oxygen atoms now have complete outer shells. Two oxygen atoms bonding by sharing electrons

20 Quick Action Molecules Practice Watch this video: Grab a partner and let s practice. Is it a molecule or a compound? Formula Molecule Compound Element Both Compound and Molecule O 2 NaCl CH 4 H 2 H Write a rule that you can follow for determining the difference in a compound and a molecule? Here is a hint All can be, but..

21 Molecules Chemical Formula is The recipe for a chemical substance. It s a type of shorthand that scientists use to describe a chemical reaction Tells the number of atoms of each element in a compound or molecule *if no number is present, the number is understood to be one Uses symbols for the elements present and subscripts (small numbers) to indicate the number of atoms of that element Ex. H 2 O water. H O 2 subscript H H O H +H + O 2 Hydrogen atoms and 1 oxygen atom

22 Molecules Chemical Equation is.. Chemical symbols that represent the process of a chemical reaction Divided into 2 parts: Reactants and products. Reactants are found on the lefthand side of the equation and the products are on the left side Each side of the equation is separated by a which means yields or produce Coefficient 2H 2 + O 2 2H 2 O 2 hydrogen molecules + 1 oxygen molecules = 2 water molecules

23 Molecules Chemical Equation is.. The number in front of the element symbol called a coefficient indicates the number of molecules. If no coefficient is present, it is understood to be 1 molecule. Molecules are separated by a + sign in the chemical equation. Coefficient 2H 2 + O 2 2H 2 O 2 hydrogen molecules + 1 oxygen molecules = 2 water molecules

24 Quick Action Molecules Practice Grab a partner and let s practice. Count the number of atoms in each molecule for theses balanced equations. 1. CH 4 + 2O 2 CO 2 + 2H 2 0 CH 4 O 2 CO 2 H Fe +3Cl 2 2FeCl 3 Fe Cl 2 FeCl P 4 O 10 + H 2 O 4H 3 PO 4 P 4 O 10 H 2 O H 3 PO 4 4

25 8/31 Classwork ISN page 1. Looking at the chemical formula, determine the number of atoms that each element contains. 2. REMEMBER that the coefficient is applied to everything behind it - - just like in a math equation! J

26 Check for Understanding Can You- Describe the differences in an element, a molecule, and a compound? Determine the number of molecules in a balanced equation?