chemical basis of life

Question 1

element

Answer 1

• only one atom
• fundamental form of matter (has mass, occupies space)
• cannot be broken down
• 94 naturally occurring; 24 are synthetic

Question 2

what are the 4 elements that make up 97% of animals

Answer 2

oxygen
carbon
hydrogen
nitrogen

Question 3

atom

Answer 3

smallest unit of an element that retains the element’s properties (consists of 3 subatomic particles)

Question 4

the 3 subatomic particles

Answer 4

protons, neutrons, electrons

Question 5

protons

Answer 5

positively charged (1 or more in the nucleus of an atom)

Question 6

neutron

Answer 6

no electric charge (1 or more in the nucleus of an atom (usually))

Question 7

electrons

Answer 7

negatively charged (occupies one of the orbitals around the atomic nucleus)

Question 8

atomic number

Answer 8

number of protons (in a neutral charge atom, the atomic number is also equal to the number of electrons)

Question 9

atomic mass

Answer 9

number of protons and neutrons

Question 10

isotopes

Answer 10

• all atoms of an element have the same number of protons
• a different type of atom of the same chemical element, each having a different number of neutrons

Question 11

isotopes are fairly common

Answer 11

isotopes differ in atomic mass but never in atomic number

Question 12

energy level shells

Answer 12

the electrons of an atom are distributed around its nucleus in orbitals

Question 13

how many energy level shells are there

Answer 13

• 7
• the valence shell is the outermost shell of an atom
• when the shell of an atom holds the maximum number of electrons, the shell is complete and stable
• an atom with an unstable outer shell tends to gain, lose, or share electrons through chemical bonding

Question 14

chemical bond

Answer 14

union between the electron structures of two or more atoms

Question 15

molecule

Answer 15

forms when two or more atoms join up (can be the same or different elements)

Question 16

compound

Answer 16

consists of 2 or more different elements in proportions that never vary (all compounds are molecules but not all molecules are compounds)

Question 17

mixture

Answer 17

two or more elements intermingle in proportions that can vary (no chemical bond, elements can be separated)

Question 18

3 types of chemical bonding

Answer 18

1. ionic
2. covalent
3. hydrogen

Question 19

ionic bonding

Answer 19

ionic bonds: atoms are opposite charge attract each other
ion: an atom that has either lost or gained one or more electrons

Question 20

covalent bonding

Answer 20

• atoms share outer-shell electrons with other atoms
• strong bonds very important in biological interactions
• non polar and polar
• electrons are shared in pairs (single, double, triple bonds)

Question 21

nonpolar

Answer 21

• distribution of charge is symmetrical
• equal sharing -> molecule electrically balanced

Question 22

polar

Answer 22

• distribution of charge is asymmetrical
• one atom slightly negative, one atom slightly positive

Question 23

hydrogen bonding

Answer 23

hydrogen bonds: a weak attraction formed when the positive end of one polarized molecule is attracted to the negative end of another
- relatively weak
- important in biological molecules
- involved in determining protein structure