Chapter 2 - Chemical Foundation of Life Flashcards
What is matter?
any substance that occupies space and has mass
What is an element?
matter that is broken down until it cannot be broken anymore or transformed chemically into another substance
How many elements are there and how many occur naturally?
118 elements
98 occur naturally, rest unstable and need to be synthesized in laboratory
What are the 4 elements common in all living organisms?
Oxygen, Hydrogen, Carbon, Nitrogen
What is C?
Carbon
Atomic mass of 6
What is H?
Hydrogen
Atomic mass of 1
What is O?
Oxygen
Atomic mass of 8
What is N?
Nitrogen
Atomic mass of 7
What is Na
Sodium
Atomic mass of 11
What is P?
Phosphorous
Atomic mass of 15
What is Cl?
Chlorine
Atomic mass of 17
What is a cm = to?
10 ^-2 m
What is a mm = to?
10 ^-3 m
What is a micrometer = to?
10 ^-6 m
What is a nanometer = to?
10 ^-9 m
What is a picometer = to?
10 ^-12 m
What is a fentometer = to?
10 ^-15 m
Which is bigger : molecules or compounds?
Molecules are bigger; a compound is a type of molecule, so all compounds are molecules, but not all molecules are compounds
What is an atom comprised of?
2 regions:
nucleus - atom’s center, contains proteins and neutrons
outer region - holds electrons in orbit around nucleus
- contains protons, neutrons, electrons
Protons vs Neutrons
Approx the same mass - 1.67 x 10 ^-24, defined as one atomic mass unit (amu) or Dalton
-Protons positive charge
-Neutrons uncharged
Atomic Number is determined by…
number of protons
-used to distinguish one element from another
Background on Electron
much smaller in mass than protons
-9.11 x 10 ^-28 grams
-1//1800 of an atomic mass unit
-don’t contribute as much to elements’ overall atomic mass
-typically ignore the mass of any electrons and calculate atomic mass based on protons and neutrons alone
Charges of Electrons and Protons and Neutrons
Protons - positive
Electrons - Negative
Neutron - Uncharged
In uncharged, neutral atoms the number of electrons…
equal the number of protons, charges cancel out
What are Isotopes?
different forms of the same atom that vary only in the number of neutrons they possess
What is the mass number?
the number of protons and neutrons in an element, bottom number of periodic table
What is the Periodic Table?
organizes and displays different elements
-created by Dmitri Mendeleev in 1869
-groups elements that share certain chemical properties
-properties are responsible for physical state at room temp (gas, liquid, solid)
What is Chemical Reactivity?
ability to combine and chemically bond with each other
-differences based on the number and spatial distribution of an atom’s electrons
When two atoms bond, what comes together first?
the electrons (outermost region)
What is the Bohr Model?
-orbitals specific distance from the nucleus; electrons fill orbitals closest to nucleus first and then orbitals of increasing energy further from the nucleus; if multiple orbitals with = energy, they fill one electron in each energy level before adding a second electron
-orbits form electron shells or energy level
Electrons at the highest level are called…
valence electrons
Electrons of outermost energy level determine…
an atom’s energetic stability and tendency to form chemical bonds with other atoms
What is the octet rule?
innermost shell has max 2 electrons but the next two electron shells can have max 8 electrons
-atoms more stable energetically with 8 electrons in a valence shell (outermost electron shell)
Atoms want to get full valence shell to be more stable, so what can they do…
give, take, share electrons with each other