Chemistry Quiz on Chemical Elements

Energy

• Energy is the ability to do work or transfer heat
• Energy has no mass and does not take up space

Forms of Energy

• Chemical: Energy stored in chemical bonds between atoms in molecules
• Mechanical: Energy in objects due to movement, position, or deformation
• Radiant: Energy carried by electromagnetic waves
• Thermal: Energy in a substance due to particle movement
• Nuclear: Energy in an atom's nucleus from bonds between protons and neutrons

Matter

• Matter is anything that has mass and takes up space
• Matter exists in three states: solid, liquid, and gas

Matter and Energy Changes

• Matter can change physically (e.g., state changes) or chemically (e.g., composition changes)

Composition of Matter (Elements)

• Elements are the fundamental units of matter, making up the periodic table
• The human body contains 27 elements
• 13 elements are considered "common" elements
• 14 elements are trace elements present in very small amounts

Common Elements in the Human Body (Major)

• Oxygen (O): 65.0% of body mass; a major component of both organic and inorganic molecules, crucial for cellular energy production
• Carbon (C): 18.5% of body mass; the primary component of all organic molecules, including carbohydrates, lipids, proteins, and nucleic acids
• Hydrogen (H): 9.5% of body mass; a component of organic molecules and influences body fluid pH
• Nitrogen (N): 3.2% of body mass; a component of proteins and nucleic acids (genetic material)

Common Elements in the Human Body (Lesser)

• Calcium (Ca): 1.5% of body mass, part of bones and teeth, crucial for muscle contraction, nerve transmission, and blood clotting: also needed for energy production (ATP)
• Phosphorus (P): 1.0% of body mass; part of bones and teeth, present in nucleic acids and many proteins and crucial for energy production (ATP).
• Potassium (K): 0.4% of body mass; important for intracellular cation, nerve impulse conduction, and muscle contraction
• Sulfur (S): 0.3% of body mass; a component of proteins, especially those involved in muscle contraction

Common Elements in the Human Body (Trace)

• A group of elements present in very minute quantities, many are part of enzymes and their activation
• Examples: Chromium (Cr), Cobalt (Co), Copper (Cu), Fluorine (F), Manganese (Mn), Molybdenum (Mo), Selenium (Se), Silicon (Si), Tin (Sn), Vanadium (V), Zinc (Zn)

Atoms

• Atoms are the building blocks of elements
• Elements are made up of many identical atoms

Subatomic Particles

• Nucleus: contains positively charged protons and uncharged neutrons

• Orbiting the nucleus: negatively charged electrons

• Atoms are electrically neutral because the number of protons equals the number of electrons

• Ions are atoms that have lost or gained electrons, becoming positively or negatively charged

Inert /Non-reactive Elements

• Inert elements are not reactive and are not part of the human body

Reactive Elements

• Reactive elements gain, lose, or share electrons to form ions which are more stable
• Gaining or losing electrons creates positive or negative ions, respectively

Chemical Reactions

• Atoms are joined through chemical bonds
• Atoms separate when the chemical bonds are broken
• Types of bonds:
  • Ionic: Electrons are transferred
  • Covalent: Electrons are shared

Chemical Bonds

• Ionic: Created when electrons are transferred to create charged ions which attract each other to create electrolytes,

  • Electrolytes (salts) readily dissolve in water and form ions, enabling current conduction

• Covalent: Created when electrons are shared

  • Covalently bonded molecules can be polar (positive and negative poles) or non-polar (no poles)

Polarity

• Polarity refers to whether a molecule has a positive and negative side (polar) or if it is electrically neutral (nonpolar)
• The polarity of molecules impacts the ease at which those molecules can cross cell membranes

Types of Chemical Reactions

• Synthesis: Smaller molecules combine to form larger molecules
• Decomposition: Larger molecules break into smaller molecules
• Exchange: Bonds are both made and broken

Reversibility

• Most chemical reactions are reversible

Factors Increasing the Rate of Chemical Reactions

• Increased temperature increases kinetic energy of molecules which increases collisions
• Increased concentration of reacting particles increases collisions

Biochemistry

• Inorganic Compounds: Lack carbon; small, simple molecules; include water, salts, and some acids and bases
• Organic Compounds: Contain carbon; large, covalently bonded molecules; include carbohydrates, lipids, proteins, and nucleic acids
• Water: Most abundant inorganic compound, crucial for lubrication, cushioning, chemical reactivity, and solubility

• Electrolytes (Salts): Compounds of cations and anions held together by ionic bonds; easily dissolve in water to release ions and conduct electricity
• Acids: Release hydrogen ions (H+)
• Bases: Release hydroxide ions (OH-) or bind hydrogen ions (H+)

• pH: measures the relative concentration of hydrogen ions (H+) in a solution

Blood Chemistry - Typical Values

• Glucose (Normal): Fasting 3.3-5.8 mmol/L (59-105 mg/dL)
• Sodium (Na+): Serum 135-145 mmol/L
• Potassium (K+): Serum 3.5-5.0 mmol/L
• Chloride (Cl-): Major extracellular anion
  • Normal levels are needed for crucial bodily functions
  • Values determined by blood tests

Important Organic Compounds

• Carbohydrates: Organic compounds containing C, H, and O; major energy source
• Lipids: Primarily contain C, H, and O; many are insoluble in water; store energy and important part of cell membranes

• Proteins: Made of amino acids; contain C, H, O, and N; key structural and functional molecules, including enzymes, hormones, and antibodies
• Nucleic Acids: Store and transfer information for protein synthesis; include DNA and RNA

• Adenosine triphosphate (ATP): Major energy currency in cells; released through breaking high-energy phosphate bonds; used for metabolic, synthetic, mechanical, and transport functions