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What is matter?
Anything with mass and volume, composed of elements.
What defines an element?
A substance that cannot be broken down chemically.
How many natural elements exist?
There are 92 natural elements.
What are essential elements?
20-25 elements needed for life.
What are the major elements that make up 96% of living matter?
Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N).
What is a compound?
Two or more elements in a fixed ratio.
What are trace elements?
Elements required in small amounts.
What is an atom?
The smallest unit retaining the properties of an element.
What are subatomic particles?
Protons, neutrons, and electrons.
What does the atomic number represent?
The number of protons in an atom.
What is mass number?
The sum of protons and neutrons in an atom.
What are isotopes?
Atoms of the same element with different neutron numbers.
What is an example of a radioactive isotope?
Carbon-14 (¹⁴C).
What determines an atom's chemical reactivity?
The number of valence electrons.
What is a covalent bond?
A bond formed by the sharing of valence electrons.
What is a molecule?
Two or more atoms held together by covalent bonds.
What is an ionic bond?
A bond formed through the transfer of electrons.
What is an anion?
A negatively charged ion.
What are hydrogen bonds?
Weak attractions between a hydrogen atom bonded to an electronegative atom and another electronegative atom.
What role do molecular shape and function play?
Shape is crucial for biological function and is determined by electron orbitals.
What is a chemical reaction?
The process of breaking and forming bonds.
What are reactants in a chemical reaction?
The starting molecules before a reaction occurs.
What is a balanced equation?
An equation where the number of atoms is conserved on both sides.
What is chemical equilibrium?
The state where forward and reverse reaction rates are equal.
What is hybridization in molecular shape?
The mixing of atomic orbitals to form new hybrid orbitals.
What are van der Waals interactions?
Temporary attractions between molecules due to fluctuating partial charges.
What determines the properties of a molecule?
The arrangement of its atoms and the types of bonds between them.
What is a polar covalent bond?
A type of covalent bond where electrons are shared unequally between atoms, resulting in partial charges.
What is a nonpolar covalent bond?
A type of covalent bond where electrons are shared equally between atoms.
How does electronegativity affect bond formation?
Atoms with higher electronegativity attract electrons more strongly, influencing bond polarity.
What are geometric isomers?
Molecules with the same formula but different spatial arrangements of atoms.
How does temperature affect chemical reactions?
Increasing temperature generally increases reaction rates by providing more energy to the molecules.
What is catalysis?
The process of accelerating a chemical reaction by adding a catalyst, which is not consumed in the reaction.
What is the difference between exothermic and endothermic reactions?
Exothermic reactions release energy, while endothermic reactions absorb energy.
What is a reaction mechanism?
The step-by-step sequence of elementary reactions by which overall chemical change occurs.
What is Le Chatelier's principle?
If a system at equilibrium is disturbed, it will shift to counteract the disturbance and restore equilibrium.
