Chemistry Basics for Biologists 2.0

Chemistry Basics for Biologists 2.0 #GoBioRams

Multiple Choice

Water contains what kinds of bonds?

• IONIC bonds

• POLAR covalent bonds

• NON-POLAR covalent bonds

• There are NO bonds holding a water molecule together.

Multiple Choice

What does ADhesion mean?

• Molecules that are the SAME are attracted to each other.

• Molecules that are DIFFERENT are attracted to each other.

Multiple Choice

What does COhesion mean?

• Molecules that are the SAME are attracted to each other.

• Molecules that are DIFFERENT are attracted to each other.

Multiple Select

If LIKE DISSOLVES LIKE and WATER is POLAR, which of the following statements is true? Check all that apply.

• Water will dissolve other POLAR molecules like food coloring.

• Water will dissolve NON POLAR molecules like oil.

• Water will dissolve IONIC compounds like salt.

Multiple Choice

What does cyt- or cyto- or -cyte equal?

• in or into or within or inside

• above or beyond or over

• cell or hollow container

• out of or away from

• below or under or less or before

Multiple Choice

What does ex- or exo- equal?

• in or into or within or inside

• above or beyond or over

• cell or hollow container

• out of or away from

• below or under or less or before

Multiple Choice

What does hypo- equal?

• in or into or within or inside

• above or beyond or over

• cell or hollow container

• out of or away from

• below or under or less or before

Multiple Choice

What does en- or em- or endo- or ent- equal?

• in or into or within or inside

• above or beyond or over

• cell or hollow container

• out of or away from

• below or under or less or before

Multiple Choice

What does hyper- equal?

• in or into or within or inside

• above or beyond or over

• cell or hollow container

• out of or away from

• below or under or less or before

Water is the Universal Solvent

• According to LIKE DISSOLVES LIKE:

• Polar water can dissolve other polar molecules.

• Polar water can dissolve ionic compounds such as salts or electrolytes.

• Chemical solutions that are dissolved in water are called aqueous solutions or _(aq) for short.

Chemical Solutions

• A solution is a mixture of two or more chemicals and it is usually a liquid in our labs.

• Usually, our solvent is water.

• The solute(s) are the chemicals that are being dissolved into the solution.

• So, a salt water solution would have water as the solvent and the salt as the solute.

Multiple Select

In a cup of coffee, which items are the SOLUTE(S)? Check all that apply.

• Boiling water

• Coffee grinds

• Sugar crystals

Why do people add milk or cream to coffee?

• What happens during a chemical reaction like cooking or baking?

• The chemicals will exchange electrons between each other.

• The elements that exchange electrons are called ions.

Ions = charged

• There are two types of ions.

• Elements that want to give away or loan out electrons are called cations or + ions.

• Elements that want to take or borrow electrons are called anions or - ions.

Acids vs. Bases

• Acids are chemicals that will damage tissue and taste sour.

• They turned litmus paper red because they had a lot of hydrogen cations or + ions in them.

• The measurement of the amount of hydrogen cations or + ions is called pH.

• Acids have a pH that is below 7.0.

Acids vs. Bases

• Bases are chemicals that will damage tissue and taste bitter.

• They turned litmus paper blue because they had very few of hydrogen cations or + ions in them.

• Bases don't have a lot of hydrogen cations but they do have a lot of OH- anions, which we can measure using pOH.

• Bases have a pH that is above 7.0.

Water has a NEUTRAL pH

• Why?

• If you write water like HOH

• The H is the acid

• The OH is the base

• H cancels out or neutralizes the OH.

Buffers

• We use buffers to help us maintain the pH of a solution.

• Think about the last time you ate something that hurt your little tummy.

• What was the food?

• If it was something spicy, you probably had to eat or drink something like milk to neutralize the acid.

• Or maybe you took TUMS^TM or Pepto-Bismol^TM to help neutralize the acid.

More on Buffers

• and how they can help your little tummy feel better.

• This video also explains how heartburn occurs in your digestive tract.

Multiple Select

Which of the following is true about ACIDS? Check all that apply.

• They taste sour.

• They taste bitter.

• They have a pH above 7.0

• They have a pH below 7.0

• They have a pH at 7.0.

Multiple Select

Which of the following is true about BASES? Check all that apply.

• They taste sour.

• They taste bitter.

• They have a pH above 7.0

• They have a pH below 7.0

• They have a pH at 7.0.

Poll

If water is NEUTRAL, what pH would it have?

• pH below 7.0

• pH at 7.0

• pH above 7.0

Multiple Choice

What are buffers used for?

• Makes things more acidic.

• Makes things more basic.

• Makes things neutral.

• Maintains the pH regardless of what that pH may be.

Water

• It is POLAR so it is the UNIVERSAL SOLVENT

• It has a NEUTRAL pH or a pH at 7.0

• What else is cool about water?

Water has hydrogen bonds

• Hydrogen bonds occurs between 2 molecules.

• One molecule must have Hydrogen (H) in it.

• The other molecule must have either Nitrogen (N), Oxygen (O), or Fluorine (F) in it, i.e. the other molecule must have N,O, or F.

• "Cheat" - NOF are all next to each other on the periodic table

Water is

• Both polar covalent AND

• Has Hydrogen bonds.

• This gives water some superhero qualities.

• Such as surface tension and why a belly flop hurts.

Water is

• Also able to float as a solid, a.k.a. ice.

• Not many solids float.

• Why is this good?

• The fish and other aquatic life will survive and thrive under the ice that forms in the Winter.

• Solid water is less dense than liquid water.

Water is

• is able to hold its temperature really, really well.

• If it is hot, it stays hot.

• If it is cold, it stays cold.

• We call this a high specific heat capacity = high ability to hold your temperature.

Multiple Select

Which of the following is true about the super molecule water? Check all that apply.

• It has a high specific heat capacity.

• It is a polar molecule that also has hydrogen bonds between molecules.

• It is acidic.

• It has a high surface tension.

• It is the Universal Solvent.

A review

• If given a periodic table, we learned last time that metals are on the left side of the periodic table.

• If given a periodic table, we learned last time that non-metals are on the right side of the periodic table.

A review

• An IONIC Bond is formed between a metal and a non-metal.

• Ionic compounds are also known as salts or electrolytes.

• When salts are dissolved in water, they will conduct electricity.

A review

• Last time we learned that NONPOLAR covalent bonds occurred between two non-metals that are exactly alike.

• Examples include O₂ and N₂.

• If given a periodic table, we will need to determine if the elements we are given will form ionic, non polar covalent, or polar covalent bonds.

A review

• A POLAR covalent bond occurs between two non-metals that are not the same.

• The example molecule that we use is water or H₂O or HOH.

• Since water is polar, it has some very important properties.

A review

• Because water is polar, it is called the Universal Solvent because of LIKE DISSOLVES LIKE.

• Polar molecules dissolve other polar molecules.

• Water can also dissolve ionic compounds, a.k.a. salts or electrolytes, which causes them to conduct electricity.

A review

• Any chemical dissolved in water forms an aqueous solution or (aq).

• Solutions are mixtures.

• The solvent is usually water while the other chemical(s) are the solute.

A review

• Water displays COhesion = when water molecules stick to each other

• Water display ADhesion = when water molecules stick to other polar molecules

• Water displays Hydrogen Bonding = due to the attraction of the H in one molecule to the O in the other molecule

A review

• These hydrogen bonds create Surface tension = surface layer of water molecules that is hard to break apart and why belly flops hurt.

• Water can hold its temperature, which means it has a high heat capacity.

• Once water starts up a container, other water molecules will follow in a process called capillary action, ex. paper towels.

A review

• Solid water is less dense than liquid water.

• Ice floats on top of the water.

• This allows living things to live and thrive under ice during the Winter.

A review

• Water is HOH which is why it has a neutral pH or a pH of 7.0.

• The H+ in HOH is the acidic part of water.

• The -OH is the basic part of water.

A review

• Acids = Damage tissue = Sour taste = Lots of H+ cations = pH below 7.0 = Turns litmus paper red

• Bases = Damage tissue = Bitter taste = Very few H+ cations = pH above 7.0 = Turns litmus paper blue

• Water is neutral.

• Acids neutralize Bases.

• Buffers are used to keep a pH at a desired pH.

Next up

We talk about 5 important big molecules for life on Earth.

Carbohydrates, Lipids, Proteins, Nucleic Acids, and High Energy Compounds.