Chemistry Basics: Matter and Atoms

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Questions and Answers

What is defined as the substance that dissolves in a solution?

Solvent

Solution

Compound

Solute (correct)

If a solution contains 15 grams of salt in 85 milliliters of water, how would this solution be expressed in percentage concentration?

20%

10%

15% (correct)

Which type of bond is formed by the transfer of electrons from a metal to a nonmetal?

Covalent bond

Ionic bond (correct)

Hydrogen bond

Metallic bond

What happens to sodium (Na) when it forms a cation?

It loses one electron. Signup and view all the answers

What is the term for a charged particle that has a negative charge?

Anion Signup and view all the answers

Which of the following statements about mixtures is true?

Mixtures involve elements that are intermixed physically. Signup and view all the answers

What determines how an atom interacts with other atoms and forms bonds?

Valence electrons Signup and view all the answers

What kind of mixture is formed when the components are not chemically changed?

Solution Signup and view all the answers

What is defined as anything that has mass and occupies space?

Matter Signup and view all the answers

Which shell in an atom is closest to the nucleus and can hold a maximum of 2 electrons?

First shell Signup and view all the answers

How are elements organized in the periodic table?

By their chemical symbol Signup and view all the answers

What is an isotope?

Atoms with the same atomic number but different mass numbers Signup and view all the answers

What percentage of the human body is composed of Oxygen?

65% Signup and view all the answers

Which of the following is a common application of unstable isotopes?

Cancer radiation therapy Signup and view all the answers

What is the primary characteristic that defines an element?

The number of protons it contains Signup and view all the answers

Which hydrogen isotope has the highest mass number?

Hydrogen-Three Signup and view all the answers

What is the term used to describe the energy required for a chemical reaction to occur?

Activation energy Signup and view all the answers

Which factor does NOT affect the rate of chemical reactions?

Color of the reactants Signup and view all the answers

How do enzymes affect chemical reactions?

They speed up reactions without altering the chemicals. Signup and view all the answers

What characteristic of water allows it to absorb heat without significantly changing its temperature?

High specific heat capacity Signup and view all the answers

Which of the following statements about enzymes is true?

Enzymes are specific for individual substrates. Signup and view all the answers

What role does a catalyst play in a chemical reaction?

It lowers the activation energy required. Signup and view all the answers

Which property of water allows it to act as a lubricant between adjacent surfaces?

Low viscosity Signup and view all the answers

Why is water referred to as the universal solvent?

Many solutes can dissolve in it fully or partially. Signup and view all the answers

What property of water allows it to dissolve hydrophilic substances?

Its molecular shape Signup and view all the answers

Which type of molecules cannot be dissolved by water?

Hydrophobic molecules Signup and view all the answers

What characterizes a hydrophilic solute?

Fully or partially charged ends Signup and view all the answers

What defines an acid in terms of its behavior in a solution?

It donates hydrogen ions Signup and view all the answers

If a solution has a pH of 8, what can be inferred about its hydrogen ion concentration?

Low hydrogen ion concentration Signup and view all the answers

How does a buffer operate in a chemical system?

By resisting changes in pH Signup and view all the answers

What is the pH of a solution that is considered acidic?

pH lower than 7 Signup and view all the answers

What happens with a one-digit change in pH?

There is a 10-fold change in hydrogen ion concentration Signup and view all the answers

What forms the basis for the body's other steroids?

Cholesterol Signup and view all the answers

Which statement is true regarding the structure of amino acids?

All amino acids contain carbon, hydrogen, oxygen, and nitrogen. Signup and view all the answers

What type of bond joins two amino acids to form a peptide?

Polar covalent bond Signup and view all the answers

Which type of protein is characterized by long nonpolar amino acid strands?

Fibrous proteins Signup and view all the answers

What is the primary function of globular proteins?

Hormonal and enzymatic functions Signup and view all the answers

What is a dipeptide?

A molecule consisting of two amino acids Signup and view all the answers

Which component contributes to the diverse properties of different amino acids?

The R (residue) group Signup and view all the answers

Which role do proteins NOT serve in the body?

Storing genetic information Signup and view all the answers

Study Notes

Matter and Chemistry

Matter is defined as anything that has mass and occupies space.
Chemistry is the scientific study of matter and its interactions.

Atoms and Elements

An atom is the smallest unit of matter that retains its properties.
Electron shells: 1st shell holds 2 electrons, 2nd shell holds 8, and 3rd shell can hold up to 18 but is satisfied with 8.
An element cannot be broken down into simpler substances by chemical means.
Elements are categorized by atomic number, which is the number of protons.
The periodic table lists elements by chemical symbols, typically derived from the element’s name (e.g., H for Hydrogen).

Elements in the Human Body

Major elements:
- Oxygen: 65%
- Carbon: 18%
- Hydrogen: 10%
- Nitrogen: 3%
- Minerals: 4%

Isotopes

Isotopes have the same atomic number but different mass numbers.
Some isotopes are unstable and release energy, which is utilized in nuclear medicine.
Common applications include cancer therapy, radiotracers, and thyroid treatment.

Mixtures and Solutions

A mixture consists of atoms from two or more elements that are physically intermixed.
A solute is the substance that dissolves, while the solvent is the substance that dissolves the solute, with water being the most important solvent in the human body.
Concentration is the amount of solute in a solution (e.g., 10% salt solution = 10g salt in 100mL water).

Molecules and Compounds

A molecule is formed by chemically bonded atoms, while a compound consists of two or more different elements (e.g., H2O).

Chemical Bonds

Ionic bonds occur when electrons are transferred between a metal atom (e.g., Sodium) and a nonmetal atom (e.g., Chlorine).
Ions are charged particles; cations have a positive charge and anions have a negative charge.
Covalent bonds occur when atoms share electrons.

Activation Energy and Reaction Rates

Activation energy is required for chemical reactions to occur, allowing atoms to collide with sufficient force.
Factors affecting reaction rates include concentration, temperature, reactant properties, and catalysts, which lower activation energy.

Enzymes

Enzymes are biological catalysts that speed up reactions without being permanently altered.
They are specific to substrates and do not change the overall chemical reaction.

Properties of Water

Water absorbs heat and changes from liquid to gas, carrying heat with it.
Acts as a cushion, lubricant, and is known as the universal solvent due to its ability to dissolve many substances.
Hydrophilic solutes are water-loving (can dissolve in water), while hydrophobic solutes do not (e.g., oils, fats).

Acids, Bases, and pH

Acids donate hydrogen ions (H+) in solution, increasing H+ concentration.
Bases are hydrogen ion acceptors, decreasing H+ concentration.
The pH scale ranges from acidic (less than 7, high H+ concentration) to basic (greater than 7, low H+ concentration).
Each unit change in pH reflects a tenfold change in H+ concentration.

Buffers

Buffers are chemical systems that resist changes in pH and are made up of a weak acid and its corresponding base.

Proteins

Proteins play essential roles: structural (hair, nails), functional (enzymes), and as energy sources.
Made up of amino acids, which possess a core structure including carbon, hydrogen, oxygen, and nitrogen.
Amino acids join to form peptides (e.g., dipeptides consist of two amino acids).

Protein Structure

Fibrous proteins consist of long strands and are primarily made of nonpolar amino acids, found in connective tissues.
Globular proteins are spherical and perform roles such as enzymatic and hormonal functions.
Protein structures have four levels of complexity.

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Description

This quiz explores the fundamental concepts of matter and chemistry. It covers the definition of matter, its properties, and the structure of atoms, including electron arrangements. Test your knowledge on these essential scientific principles.