chapter 2, basic chem Flashcards
What is matter?
Anything that has mass and takes up space.
Define an element.
A pure substance consisting of only one type of atom (e.g., oxygen, carbon).
What is an atom?
The smallest unit of an element that retains its properties.
What is a proton?
Positively charged subatomic particle, found in the nucleus.
What is a neutron?
Neutral subatomic particle, found in the nucleus.
What is an electron?
Negatively charged subatomic particle, orbits the nucleus.
What defines an ionic bond?
Transfer of electrons from one atom to another, creating charged ions (e.g., NaCl).
Define a covalent bond.
Sharing of electrons between atoms (e.g., H₂O).
What is a nonpolar covalent bond?
Equal sharing of electrons (e.g., O₂).
What characterizes a polar covalent bond?
Unequal sharing of electrons, creating partial charges (e.g., H₂O).
What is a hydrogen bond?
Weak attraction between a hydrogen atom and another electronegative atom (e.g., in water molecules, DNA structure).
What are Van der Waals forces?
Weak, temporary interactions between molecules.
What is cohesion in relation to water?
Water molecules stick together due to hydrogen bonding.
Define adhesion.
Water molecules stick to other surfaces.
What is surface tension?
The cohesive forces at the surface of water.
What is a solvent?
A substance that dissolves other substances (e.g., water is the universal solvent).
What does hydrophilic mean?
Water-loving substances (dissolve in water, e.g., salt, sugar).
What does hydrophobic mean?
Water-fearing substances (do not dissolve in water, e.g., fats, oils).
What does the pH scale measure?
Hydrogen ion concentration (0-14).
What is an acid?
pH below 7; high H⁺ concentration (e.g., stomach acid).
Define a base (alkaline).
pH above 7; low H⁺ concentration (e.g., ammonia).
What is a neutral pH?
pH of 7 (e.g., pure water).
What is a buffer?
A substance that resists changes in pH (e.g., bicarbonate in blood).
What are carbohydrates?
Provide energy; made of monosaccharides (e.g., glucose).
