Atoms and Isotopes
What are the three main components of an atom and their respective charges?
Proton - +1
Neutron - 0
Electron - -1
How is a covalent bond formed?
Sharing of electrons between two atoms
What does pH mean?
Concentration of hydrogen ions
What percentage of living tissue is made of H, C, N, O, P, S?
98%
What is conservation of matter?
Matter is not created nor destroyed in reactions
What is the mass of a proton, neutron, and electron
Proton - 1 Dalton
Neutron - 1 Dalton
Electron - negligible
How is a polar covalent bond different from a nonpolar covalent bond?
Polar = electrons are unequally shared creating partial charges
Nonpolar = equally shared electrons
A solution with pH 3 has how many more protons than pH 7?
10,000x more
How do isotopes of different atoms vary?
They have different amounts of neutrons
Can more than one covalent bond form between two atoms
Yes, double and triple bonds are possible
What does the atomic number represent?
The number of protons in an atom, as well as the number of electrons in a neutral atom
What are cations and anions?
Cation = + charged
Anion = - charged
Chemically, what is an acid? What is a base?
An acid releases H+
A base accepts H+
What makes water unique? Why do organisms need to keep hydrated?
- Solid water is less dense than liquid water
- high heat capacity
- high heat of vaporization
- water sticks (cohesion or adhesion)
- Polar substance that is soluble to other polar substances.
Water is the medium of virtually all biochemical reactions
What kind of forces can form between nonpolar molecules?
van der Waals forces
Why isn't the atomic mass always a whole number?
It is an average of the different isotopes
Are salts formed by covalent or ionic bonding?
Ionic bonding
Why are weak acids and bases important in the body?
They maintain stable conditions for biomolecules to function in
What is a chemical compound?
A pure substance made up of two or more different elements bonded together in a fixed ratio
Where would you expect strong acids and bases in the body?
The stomach and digestive system
What makes radioisotopes different from other isotopes?
They are unstable and give off radiation
Compare hydrogen bonds to covalent and ionic bonds
Hydrogen bonds are weaker and form between molecules due to partial charges
What role do buffers play in living organisms?
Help resist changes in pH to maintain stability of the organism
What is stronger in a cell? 10 covalent bonds or 1,000 noncovalent bonds.
The 1,000 noncovalent bonds
I have a sample of 50 grams of radium-228, which has a half-life of 5.75 years.
If I forget about the sample in a shoebox for 17.25 years, how much of the sample would I have left when I find it?
6.25 Grams