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Chemical Context of Life Flashcards
Matter
Anything that takes up space and has mass; composed of chemical elements and compounds.
Element
Pure substances that cannot be broken down to other substances by chemical reactions.
Compound
Substance formed from two or more elements in fixed ratios; possess emergent properties different from those of individual elements.
Essential elements
About 20–25% of the 92 natural elements required for life.
Major elements
(96% of living matter): Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).
Trace elements
Elements required by an organism in only minute quantities.
Elements in the human body (6 major)
Oxygen, Carbon, Hydrogen, Nitrogen, Calcium, Phosphorus.
(O,C,H,N,Ca,P)
Atoms
The smallest unit of matter that compose elements consisting of protons, neutrons, and electrons.
Neutrons
No charge
Protons
Positive charge
Electrons
Negative charge; surrounding the nucleus in clouds.
Atomic number
The number of protons in an atom's nucleus.
Mass number
The sum of protons plus neutrons in an atom's nucleus.
(proton + neutron = mass number)
Isotope
2 atoms of the same element with different numbers of neutrons.
Radioactive isotopes
Isotopes that decay spontaneously, giving off particles and energy. Often used in diagnostic tools in medicine.
Cation
A positively charged ion.
Radiometric Dating
A method used to determine the age of materials by measuring the decay of radioactive isotopes present in them.
Energy
the capacity to cause change
Potential energy
the energy stored in an object due to its position or arrangement.
Electron shells
where electrons are found, each shell corresponding to a different potential energy level.
Anion
A negatively charged ion.
Chemical bonds
attractive forces holding atoms together
Single bond
sharing one pair of elements
Double bond
sharing two pairs of elements
Nonpolar covalent bond
A type of covalent bond where electrons are shared equally between atoms, resulting in no charge separation.
Ionic bond
The attraction between oppositely charged ions.
Cation
a positively charged ion
Anion
a negatively charged ion - has more electrons than protons.
Compound
a combination of two or more different elements
Molecule
Two or more atoms held together by covalent bonds.
Covalent bond
The sharing of a pair of valence electrons by two atoms.
Electronegativity
An atom's attraction for the electrons in a covalent bond.
Polar covalent bond
A bond where one atom is more electronegative and electrons are not shared equally.
Van der Waals interactions
weak attractions due to temporary changes in molecules
Hydrogen bond
A weak bond formed between a hydrogen atom covalently bonded to one electronegative atom.
Valence electrons
Electrons in the outermost shell of an atom that determine its chemical behavior.
Chemical reaction
The making and breaking of chemical bonds.
Reactants
The starting molecules of a chemical reaction.
Products
The resulting molecules of a chemical reaction.
Chemical equilibrium
When the forward and reverse reactions occur at the same rate.
Hybrid orbitals
Orbital shapes that result from the combination of s and p orbitals.
Molecular shape
The three-dimensional arrangement of atoms in a molecule.
Functional groups
Specific groups of atoms within molecules that determine their chemical reactivity.
Photosynthesis
A chemical reaction powered by sunlight that converts carbon dioxide and water into glucose and oxygen.
Half-life
The time required for half of a sample of a radioactive isotope to decay.
Ionic compound
Compounds formed by ionic bonds, typically found as crystals.
Molecular mimic
A molecule that has similar structure to another and can bind to the same receptor.
Structural formula
A representation of a molecule that shows the arrangement of atoms.
Molecular formula
A simplified version of the structural formula that indicates the number and type of atoms.
Bonding capacity
An atom's ability to form bonds, determined by its valence.
Nitrogen (N) is more electronegative than hydrogen (H). Which of the following is a correct statement about the atoms in ammonia (NH3)?
a) Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.
b) Ammonia has an overall negative charge.
c) Ammonia has an overall positive charge.
d) The nitrogen atom has a partial positive charge; each hydrogen atom has a partial negative charge.
Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge.
3H2 + N2 ↔ 2NH3
Which of the following is true for the above reaction?
a) hydrogen and nitrogen are the reactants of the reverse reaction.
b) the reaction is nonreversible.
c) ammonia is being formed and decomposed simultaneously.
d) only the forward or reverse reactions can occur at one time.
c) ammonia is being formed and decomposed simultaneously.
Equilibrium
the rates of the reverse and forward reactions are equal.
How many electrons are in H- and H+
2,0.
Note 
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