Elements and Compounds Notes 2016.notebook January 15, 2019

Class Notes: Elements 

and Compounds

They are both "Pure Substances"

Periodic table asap 2 min.https://www.youtube.com/watch?v=VgVQKCcfwnU&t=2s

WHAT IS A

"PURE SUBSTANCE?"

Elements and Compounds Notes 2016.notebook January 15, 2019

Pure substance: When all the particles in a substance are alike

What are four examples?

What is the simplest pure substance?

If you melt IRON, does it become a simpler substance?

WHY NOT???

Atom: Smallest part of an element that has the properties of that element.

Chemical symbol: Shorthand way to write the elements: Carbon ____ Hydrogen ____ Calcium ___ Gold ____

Atom: Smallest part of an element that has the properties of that element.

Chemical symbol: Shorthand way to write the elements: Carbon ____ Hydrogen ____ Calcium ___ Gold ____

Elements and Compounds Notes 2016.notebook January 15, 2019

Compound: Two or more elements chemicallycombined

Carbon + Oxygen = Carbon Dioxide= CO2

Hydrogen + Oxygen = Water= H2 O

Sodium + Chlorine = Sodium Chloride= NaCl

Elements Compound

Na Cl

Properties of the elements are very different than properties of the compound itself.

Highly reactive!                  Poisonous!                  We put on food!

https://www.youtube.com/watch?v=ODf_sPexS2Q

Elements and Compounds Notes 2016.notebook January 15, 2019

Compounds: Pure substances made of more than one elementWater = Carbon dioxide =

Molecules: Pure substances: 2 or more atoms chemically bonded together.

2 atoms of oxygen = O2

2 atoms of chlorine = Cl2Molecule but not compound!! (same element)

2 atoms hydrogen + one of oxygen = H2 OMolecule and compound!!

Chemical Formula: Combinations of chemical symbols to represent chemical substances. Ammonia = NH

Rubbing Alcohol = C H OH

Coefficient: Large number in front that tells you how many of that formula

3 7

3

2H2O

Ammonia Elements:

Alcohol Elements:

Elements and Compounds Notes 2016.notebook January 15, 2019

Where is Subscript placed: to right of element symbol

What does Subscript tell you? The number of atoms of element in the compound

When there's only One atom, the subscript 1 is ______ written.

Coefficient: Large number in front that tells you how many of that formula

Subscript

2H2O

Elements and Compounds Notes 2016.notebook January 15, 2019

Chemical Formula for Carbon Dioxide

How many atoms of carbon? _____ oxygen? ____

If chemical symbols are like letter, and chemical formulas

are like words, chemical equations are like SENTENCES!

Elements and Compounds Notes 2016.notebook January 15, 2019

Chemical Equation: Shorthand method to describe chemical reactions using chemical formulas and other symbols

C + O2 CO2

Chemical Equation for Carbon Dioxide

Elements and Compounds Notes 2016.notebook January 15, 2019

The Law of Conservation of Mass:The mass of all substances BEFORE a chemical reaction is the SAME as AFTER the chemical reaction!

(Count the atoms!)

Elements and Compounds Notes 2016.notebook January 15, 2019

Does this reaction show Law of Conservation of Mass?

Learn to Count Atoms!

Elements and Compounds Notes 2016.notebook January 15, 2019

LET'S PRACTICE COUNTING!

2.

3.

4.

5.

CarbonOxygen

Elements and Compounds Notes 2016.notebook January 15, 2019