Atomic Structure
What is matter?
Anything that takes up space and has mass.
What are valence electrons?
Electrons in the outermost electron shell that determine how atoms bond.
Why is water a polar molecule?
Oxygen pulls electrons more strongly than hydrogen, causing unequal sharing and creating slightly positive and negative regions.
Why does ice float?
Ice is less dense than liquid water because water expands when frozen.
What ion makes a solution acidic?
Hydrogen ions (H⁺).
What are the three subatomic particles, their charges, and locations?
Why do atoms form chemical bonds?
To become more stable by filling their outer electron shell.
What type of bond exists between water molecules?
Hydrogen bonds.
Why does water have a high heat capacity?
Hydrogen bonds allow water to absorb a lot of heat without a large temperature change.
What ion makes a solution basic?
Hydroxide ions (OH⁻).
Which particle determines what element an atom is?
Protons.
What is the octet rule?
Atoms are most stable when their outer shell contains 8 electrons.
Water sticking to itself is called what?
Cohesion.
Why does sweating cool your body?
Water has a high heat of vaporization, meaning evaporation requires lots of energy and removes heat from your body.
Is pH 3 acidic or basic? Is pH 10 acidic or basic?
An atom has:
What element is it, and what is its mass number?
Sodium loses an electron to chlorine. What type of bond forms?
Ionic bond.
Water sticking to other surfaces is called what?
Adhesion.
A plant transports water from roots to leaves. Which properties help?
Cohesion and adhesion.
What is a buffer?
A substance that resists changes in pH by absorbing excess H⁺ or OH⁻.
What are isotopes?
Atoms of the same element that have different numbers of neutrons, resulting in different mass numbers.
Compare ionic and covalent bonds.
Ionic:
Covalent:
Explain why water can dissolve salt.
Water’s polarity allows it to surround and separate charged ions (Na⁺ and Cl⁻), causing salt to dissolve.
Explain why water is essential for life.
Water supports life because it dissolves substances, regulates temperature, transports materials, and has properties that allow organisms to function.
Why is maintaining blood pH important?
Cells and enzymes require a stable pH to function properly. Large changes can disrupt body processes and be dangerous.