Chemistry Chapter: Matter and Atoms

Matter and Elements

• Matter is anything that occupies space and has mass.
• Elements are substances that cannot be broken down into simpler substances.
• Compounds are formed when two or more elements combine in a fixed ratio.
• Trace elements are essential for various biological functions, such as iron for red blood cells and iodine for hormone regulation.

Atoms

• Atoms are the smallest unit of an element that retains its chemical properties.
• Atoms are made up of subatomic particles: protons, neutrons, and electrons.
• Protons carry a positive charge, neutrons have no charge, and electrons carry a negative charge.
• Protons and neutrons reside in the atomic nucleus, while electrons orbit the nucleus.

Atomic Number and Mass Number

• The atomic number of an element is the number of protons in its nucleus.
• The mass number of an element is the total number of protons and neutrons in its nucleus.
• Atomic mass is approximately equal to the mass number.

Isotopes

• Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.
• Radioactive isotopes are unstable and decay over time, releasing energy as radiation.

Radioactive Isotopes

• Radioactive isotopes are used in medical diagnosis and treatment.
• They can be used to track metabolic processes, detect cancer cells, and deliver radiation therapy.
• Radiation can be harmful to healthy cells, causing side effects and potentially increasing cancer risk.

Chemical Bonds

• Chemical bonds form between atoms due to interactions between their electrons.
• Covalent bonds involve the sharing of electrons between two nonmetals:
  • Polar covalent bonds: electrons are shared unequally.
  • Nonpolar covalent bonds: electrons are shared equally.
• Ionic bonds form when electrons are transferred from a metal to a nonmetal.
• Hydrogen bonds are weak interactions between a hydrogen atom and a highly electronegative atom like oxygen or nitrogen.

Properties of Water

• Water is a polar molecule due to the uneven distribution of electrons in its covalent bonds.
• Water's polarity allows it to form hydrogen bonds with other water molecules and other polar substances.
• Water has several important properties that support life:
  • High boiling point: due to strong hydrogen bonds.
  • High heat capacity: water can absorb a lot of heat without significant temperature changes.
  • Universal solvent: water's polarity allows it to dissolve many substances.
  • High surface tension: water molecules at the surface are strongly attracted to each other.
  • Cohesive and adhesive properties: water molecules stick to each other (cohesion) and to other polar surfaces (adhesion).

Biological Macromolecules

• Carbon is the basis of all organic compounds, including biological macromolecules.
• Carbohydrates serve as fuel and structural components for living organisms.
• Monosaccharides are simple sugars that act as monomers—building blocks for larger carbohydrates.
• Polysaccharides are polymers made up of many monosaccharide units:
  • Starch: energy storage in plants.
  • Glycogen: energy storage in animals.
  • Cellulose: structural component of plant cell walls.

Explore the fundamental concepts of matter and elements with this quiz. Test your understanding of atoms, their structures, atomic numbers, and isotopes. This quiz covers essential topics that form the basis of chemistry education.