Chapter 2 Flashcards
The Chemical Basis of Life
matter
occupies space and has mass
elements
pure substance; cannot be broken down into anything else
compound
substance consisting of two or more elements
main four elements in the body
Carbon, Hydrogen, Oxygen, Nitrogen (CHON)
emergent properties
characteristics of compounds not usually found in the base elements
trace elements
elements needed by the body in small quantities; iron, iodine, fluorine, etc.
atom
smallest unit of matter able to retain elemental properties
proton
- positive charge
- in nucleus
- has mass
electron
- negative charge
- in electron shell
- no mass
neutron
- neutral charge
- in nucleus
- has mass
nucleus
atoms central core
atomic number
number of protons
atomic mass
number of protons and neutrons
isotopes
same element but with different atomic masses (C12 and C13)
radioactive isotope
unstable isotope with decaying nucleus; gives off particles and energy
why are radioactive isotopes useful ?
can be used to track and follow certain molecules and show accumulation of certain molecules
electron shell
levels of electrons at certain distances from nucleus; determines chemical properties of the atom
electron levels 1-4 hold how many electrons each ?
2, 8, 8, 18
chemical bonds
attraction between the electrons in two atoms
what is the goal of chemical bonds ?
to complete the valence electron shell
ionic bond
transferring electrons
covalent bond
sharing ≥ 1 electrons
how many covalent bonds for Carbon, Hydrogen, Oxygen, Nitrogen
4, 1, 2, 3
molecule
≥ 2 atoms covalently bonded
electronegativity
attraction of atoms for electrons in covalent bonds
nonpolar covalent bond
electrons shared equally between atoms with similar electronegativity
polar covalent bond
electrons shared equally between atoms with different electronegativity
why are water molecules polar covalent bonds ?
the slightly negative Oxygen and the slightly positive Hydrogen
ionic charges in elements are obtained how ?
from the transferring of electrons between one atom to another
ion
atom(s) gained / lost an electron; gaining a positive or negative charge
what holds together ions in a crystal of table salt
ionic bond (Na+ and Cl-)
hydrogen bond
slightly positive Hydrogen atom bonds covalently with another slightly negative atom
polar molecule
molecule with polar covalent bond; unequal electron distribution
what enables neighboring water molecules to hydrogen bond
the slightly positive Hydrogen atom of one molecule and the slightly negative Oxygen atom in another
chemical reactions
make / break / rearrange bonds; leads to a change in composition of matter
reactant
starting material in a chemical reaction
product
ending material in a chemical reaction
why is sold water less dense than liquid water
due to the hydrogen bonds; the bonds freeze spaciously rather then densely
how can freezing water crack a boulder ?
the expanding hydrogen bonds will expand in the cracks and then crack the boulder itself
solution
homogenous mixture of ≥ 2 substances in a liquid
solvent
dissolving agent of a solution
universal solvent
water
solute
substance being dissolved in a solution
aqueous solution
solution using water as solvent
why is water the universal solvent ?
(idk) waters polarity; the slightly positive Hydrogen atoms and the slightly negative Oxygen atoms
acid
increases Hydrogen (H+) ion concentration by donating H+ ions
base
reduces hydrogen (H+) ions by donating hydroxide ions (OH-)
pH scale
scale of 0 - 14 (acidic - basic)
buffer
substance that’s minimizes changes in pH