The Chemical Context of Life

Question 1

element

Answer 1

An ELEMENT is a substance that can not be broken down into other substances by chemical reactions.

Question 2

matter

Answer 2

anything that takes up space and has mass

Question 3

compound

Answer 3

A COMPOUND is a substance of two or more different elements combined in a fixed ratio.

Question 4

essential elements

Answer 4

96% of living matter : carbon (C), oxygen (O), hydrogen (H), nitrogen (N) phosphorus (P), sulfur (S), calcium (Ca), potassium (K) and a few other elements make the remaining 4% of living matter

Question 5

trace elements

Answer 5

TRACE ELEMENTS are those required by an organism in only minute qunatities. eg.: iron

Question 6

atom

Answer 6

An ATOM is the smallest unit of matter that still retains the properties of an element.

Question 7

mass of atoms, subatomic particles, molecules: UNIT

Answer 7

daltons, atomic mass unit, amu

Question 8

John Dalton

Answer 8

British scientist, 1800, atomic theory

Question 9

atomic number

Answer 9

number of protons eg.: 2He indicates that helium has 2 protons

Question 10

mass number

Answer 10

sum of protons plus neutrons in the nucleus of an atom, eg. 23/11 Na -> Na has 11 protons, 12 neutrons

Question 11

isotopes

Answer 11

Atoms of the same element have the same number of protons, but a different number of neutrons

Question 12

radioactive isotope

Answer 12

A radioactive isotope is one in which the nucleus decays spontaneously, giving off particles and energy.

Question 13

energy

Answer 13

capacity to cause change

Question 14

ion

Answer 14

charged atom or molecule

Question 15

orbital

Answer 15

the threedimensional space where an electrone is found 90% of the time; no more than 2 electrons can occupy a single orbital

Question 16

strongest chemicals bonds

Answer 16

covalent bonds and ionic bond

Question 17

covalent bond (Elektronenpaarbindung)

Answer 17

A covalent bond is sharing of a pair of valence electronsby two atoms. eg. hydrogenbond

Question 18

molecule

Answer 18

two or more atoms held together by covalent bonds constitute a molecule

Question 19

valence

Answer 19

the atoms bonding capacity

Question 20

electronegativity

Answer 20

attraction of a particular kind of atom for the electrons of a covalent bond

Question 21

nonpolar covalent bond

Answer 21

a bond, in which electrons are shared equally

Question 22

polar covalent bond

Answer 22

one atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally

Question 23

cation

Answer 23

positive ion

Question 24

anion

Answer 24

negative ion

Question 25

ionic bond

Answer 25

Because of their opposite charges, cations and anions attract each other. This attraction is called ionic bond. Compounds formed by ionic bonds are called ionic compounds or salts.

Question 26

Van der Waals Kräfte

Answer 26

schwache Kräfte zwischen Molekülen; sind umso stärker, je länger die Molelüle; erhöhen die Siedetemperatur; enstehen aufgrund von Ladeschwerpunkten zwischen den Molekülen, da Elektronen sich nicht gleichmäßig um den Atomkern bewegen