Lecture Notes Review: Atomic Structure, Bonding, pH, Carbohydrates, and Experimental Controls

Flashcards cover atomic structure, types of chemical bonds, pH concepts, Benedict's and Lugol's tests for sugars and starch, carbohydrate classifications, and the purpose of experimental controls, as presented in Pages 1-5 of the notes.

What is the basic unit of a chemical substance?

Atom.

What does the atomic number represent?

Number of protons in the nucleus.

What does atomic mass represent?

Total number of protons plus neutrons in the nucleus.

Where are protons and neutrons located inside the atom?

In the nucleus.

Which subatomic particle orbits the nucleus?

Electrons.

What is a chemical bond?

An interaction between atoms that holds them together.

What is a covalent bond?

Sharing of electrons.

What is a nonpolar covalent bond?

Equal sharing of electrons between atoms.

What is a polar covalent bond?

Unequal sharing of electrons between atoms.

What is an ionic bond?

Attraction between oppositely charged ions, often formed by loss or gain of electrons.

What does pH measure?

The concentration of hydrogen ions in a solution.

What is the pH scale range?

1 to 14.

What pH range indicates an acid?

Approximately pH 1 to 6.9.

What pH range indicates a base?

Approximately pH 7.1 to 14.

What pH value indicates neutrality?

pH 7.

Which direction does increasing hydrogen ion concentration push the pH scale?

More H+ makes the solution more acidic (lower pH).

What is pH paper used for?

To predict the pH of a liquid by color change.

What does Benedict's reagent test for?

Reducing sugars.

What colors indicate a positive Benedict's test?

Green, yellow, orange, or red color indicates reducing sugars; blue indicates negative.

What is the positive control for Benedict's test?

5% glucose solution.

What is the negative control for Benedict's test?

DI water.

What does Lugol's iodine test detect?

Presence of starch (polysaccharide).

What color indicates presence of starch in Lugol's test?

Blue-black color.

What color indicates the absence of starch in Lugol’s testing ?

Yellow-brown color

What complex forms in Lugol's iodine test?

Starch-iodine complex (amylose-iodine complex).

What is the positive control for Lugol's test?

Starch solution.

What is the negative control for Lugol's test?

DI water.

What are monosaccharides?

Single, simple sugars; building blocks for larger carbohydrates.

What are disaccharides?

Two monosaccharides linked together.

What are oligosaccharides?

3-7 monosaccharides linked together.

What are polysaccharides?

Complex carbohydrates made of 12+ monosaccharides; energy storage molecules.

Name two examples of polysaccharides mentioned.

Starch (plants) and Glycogen (animals).

What is Benedict's reagent used for in the context of reducing sugars?

To test for reducing sugars by oxidizing them; blue Cu2+ is reduced to brick-red Cu2O.

What is the purpose of positive and negative controls in experiments?

To ensure procedures work, detect contamination, and provide a reference point for comparison.

What would be a positive control example when testing for Vitamin C in foods?

Vitamin C solution.

What would be a negative control example in Vitamin C testing?

Water.

What is the role of starch and glycogen in biology?

Starch stores energy in plants; glycogen stores energy in animals.