ED: ch 2 Flashcards
Name the four chemical elements that make up around 96% of living matter.
CHON
how are some other elements are essential to life, despite their low prevalence in living organisms.
-Fe is involved in chlorophyll production, deficiency of it causes yellowing of plant
-Symptom of Iodine Deficiency
Enlargement of the thyroid gland,(Goiter) Thyroid hormones control metabolism and development
-Fe deficiency in animals causes Anemia (low red blood cell count)
what is atomic number
proton number
what is mass number
total number of protons and neutrons in the nucleus of an atom.
what is atomic weight
atomic mass is the mass of an atom
where 1 dalton is defined as ¹⁄₁₂ of the mass of a single carbon-12 atom,
what are isotopes
same proton number different neutron number/ same atomic number different mass number
what are radioactive isotopes
nucleus decays spontaneously, giving off particles and energy.
what are the uses of radioactive isotopes
used to destroy cancer cells and as tracers to tract substances trough the body to identify (diagnose) cancer and other diseases and for Carbon-14 dating
how can an electron move up/down a shell?
gain/lose energy
which shell has the most amount of energy?
valence shall
what is the max number of electrons that shell 1 and 2 can hold?
1= 2e
2=8e
what is the chemical behaviour of an atom determined by?
distribusion of electrons in its electron shells
state the chemical bonds strongest to weakest
1- covalent
2- ionic
3-h-bonds
4- Van der Waals interactions
what are the two ways atoms can fill their valence shell
by sharing electrons with another atom like in covalent bonding or it can completely transfer electrons like in ionic
what is electronegativity?
The ability of an atom to attract electrons in a chemical bond to itself.
Non-polar vs Polar covalent bonding and exceptions
- A covalent bond is non-polar if both atoms are the same and equally electronegative
- A covalent bond is polar if one of the atoms is more electronegative – Electrons of a polar covalent bond are pulled closer to the more electronegative atom
-Electronegativity difference BUT the molecule is symmetric, therefore the dipoles cancel out
describe ionic bonding
A positively charged ion is called a cation, while a negatively charged ion is called an anion. Because of their opposite charges, cations and anions attract each other; this attraction is called an ionic bond.
-cation loses e, anion gains e
why is ionic bonding weaker in biology?
most biological reactions take place in water and ionic bonds are able to break down in water
What is h-bonding?
Weak attraction between one electronegative atom (F,N,O) and a hydrogen atom that is linked to another electronegative atom
what are Van der Waals interactions?
Non-polar molecules have transient positively and negatively charged region because electrons are in constant motion and some of the time the electrons may be distributed asymmetrically causing one region to be +ve or -ve and to attract and interact with the opposite charge temporarily
What is a chemical reaction?
The making and breaking of chemical bonds, leading to changes in the composition of matter
what is a chemical equillibrium?
- chemical equilibrium is the state in which both reactants and products are present in concentrations which have no further tendency to change with time, so that there is no observable change in the properties of the system.
- No net effect on the concentrations of reactants and products
what is one of the factors affecting the rate of a reaction
The greater the concentration of reactant/products molecules, the more frequently they collide with one another and have an opportunity to react and form products/reactants.
