Chapter 2: Chemistry By PresenterMedia.com PresenterMedia.com

Basic unit of Matter Atoms Center of the atom. Contains protons and neutrons Do not contain any charge Negatively charged. Attracted to protons. Constantly moving around them Nucleus Electrons Protons Neutrons Positively charged.

Elements Pure substance of 1 type of atom Atomic Number Number of protons and electrons Compounds Substance made up of more than 1 element Humans made up of over 60 elements 99% of mass is oxygen, hydrogen, carbon, nitrogen, calcium, and phosphorous Elements and Compounds

IONIC BONDS Electrons are transferred from one element to another Causes elements to become ions Positively charged if losing an electron Negatively charged if gaining an electron Ex: Salt (NaCl) Electrons are shared between 2 elements The electron can move back and forth between them Ex: Water (H2O) COVALENT BONDS Chemical Bonds Ionic Bonds vs Covalent Bonds A callout, this can be edited or deleted

Chapter 2: Chemistry

Hydrogen is very good at bonding to other elements Allows water to bond in different ways Cohesion Water molecules attaching to each other Ex: Water staying together when poured out Adhesion Water molecules attaching to other molecules Ex: Water sticking to glasses and bottles Hydrogen and Oxygen Water Molecules and Properties

Solutions Water and a substance mix evenly together Cannot tell the difference between the two substances Ex: Water and Food Coloring Suspensions Water and a substance do not mix together Properties of both can be seen separately Ex: Oil and Water Properties of Water Solutions and Suspensions

Measurement of hydrogen ions in a solution pH below 7 is an acid (0-6.9) pH above 7 is a base (7.1-14) 7 is neutral (water) Buffers Weak acids or bases that can react to strong ones to help keep balance pH Scale A second line of text here

Chapter 2: Chemistry

What is a chemical reaction? Process that changes one set of chemicals into another Some release energy while others use energy During process, chemicals bonds are broken and formed Chemical reactions give off their own energy Activation energy Energy needed to start a chemical reaction Bare minimum needed Chemical Reactions

What is a catalyst? A substance that helps speed up a chemical reaction They work by lowering the activation energy needed What is an enzyme? A protein A form of a catalyst Usually work on one type of chemical reaction in the body Can be controlled by factors like temperature and pH Molecules usually control when they are turned on and off Enzymes

Chapter 2

1. What 3 particles make up an atom Answer: Protons (Positive Charge), Neutrons (No Charge), Electrons (Negative Charge) 2. How do compounds differ from elements in them? Answer: Compounds can have different physical properties from the elements. They can change forms. Ex: Water. Oxygen and hydrogen are gases and combine to liquid 3. What are the main kinds of chemical bonds? Ionic Bonds: Electrons are transferred from one to other Covalent Bonds: Electrons are shared between elements Nature of Matter Section 1:

4. How does the structure of water lead to its special properties? Answer: Water is polar. Means it can form many bonds. Allows for water to perform cohesion and adhesion 5. How does water’s polarity affect its properties as a solvent? Answer: It allows for water to be part of a solution and have fully diluted substances in it. It can also be part of a suspension which does not mix with water 6: Why is it important for cells to buffer solutions? Answer: Allows for homeostasis to be maintained in a body to keep it healthy. Homeostasis: Maintain internal environ. Properties of Water Section 2:

7. What happens to chemical bonds in reactions? Answer: Chemicals bonds are broken in order to create a reaction. In other cases, chemical bonds are formed when reactions bring together substances 8. How do energy changes affect if a chemical reaction will happen? Answer: Activation energy is needed when it comes to chemical reactions that need to take in energy. 9. What role do enzymes play in living things and what affects their function? Answer: Enzymes speed up chemical reactions. They can be affected by changes in temperature, pH, and control molecules. Chemical Reactions and Enzymes Section 4:

Chapter 2 : Chemistry

1. What are the 3 particles that make up an atom? 2. What are the 2 main types of chemical bonds and how are they different? 3. Why is it important for cells to buffer solutions? 4. What happens to chemical bonds in reactions? 5. What role do enzymes play in living things and what affects their function? 2-3 sentences per question Quiz Questions