Chem elements and chem bonds Wk 1

Question 1

What are chemical elements? What are they important for?

Answer 1

simplest form of matter
- Important for teeth, bones, enzyme functions

Question 2

Describe atoms. What makes up it’s nucleus? What is it’s charge?

Answer 2

smallest stable unit of matter
-cant be broken down to simpler substance by chemical means
-nucleus; p=pos e=neg n=neutral
-electrically neutral as number of e=p

Question 3

What creates atomic number

Answer 3

number of p in nucleus=number of e

Question 4

Define electrolytes

Answer 4

mineral salts essential for nerve and muscle function

Question 5

Define electron cloud. Describe energy levels and what they hold

Answer 5

orderly series of energy levels
-1st=2 e
-2nd and 3rd= up to 8 e
outermost shell=valence shell

Question 6

Describe valence shell electrons. What happens when it’s full/not full

Answer 6

valence shell=outermost level-surface
-determine chem bonding properties of atom
-if outer filled atom=inert/unreactive/noble
-if outer not filled-reactive

Question 7

Define isotopes. What occurs when number of neutrons increase?

Answer 7

varieties of element differing only in number of neutrons
-isotopes of element are chemically similar as same number of valence electrons
-increase neutrons=increase atomic weight

Question 8

Define molecule

Answer 8

chemical particle comprising two or more atoms united by chemical bond

Question 9

Define compound

Answer 9

molecule comprising two or more different elements

Question 10

Define molecular formula

Answer 10

identifies constituent element and number of atoms present

Question 11

Define structural formula

Answer 11

identifies location of each atom

Question 12

Define chemical bonds

Answer 12

hold atoms together within molecule or attract one molecule to another

Question 13

Define ions and ionisation reactions

Answer 13

ions=charged particles (atom or molecule) with unequal number of protons and electrons
-opposingly charge will attract

ionisation=transfer of electrons from one atom to another

Question 14

Differ between anions and cations

Answer 14

Anion: gains electrons(net negative)
Cation: loses electrons (net positive)

Question 15

Describe ionic bond

Answer 15

transfer of electrons
-electrical attraction between positive and negative

Question 16

Describe covalent bonds

Answer 16

sharing of electrons
-complete outer shell by sharing e with other

Question 17

Differ between non-polar and polar covalent bonds

Answer 17

nonpolar covalent bonds: equal sharing of electrons - very strong
polar covalent bonds : unequal sharing of electrons - weaker

Question 18

Describe hydrogen bonds. How are H2O attracted to one another?

Answer 18

Weak attraction between slight pos H atom in one molecule and slight neg O/N in another
-H2O are attracted to each other by H bonds (pos charge of H and neg charge of O, N, F)

Question 19

Describe Vander Waal forces and effect of changing electron density

Answer 19

Weak, brief attractions between neutral atoms
-Fluctuation in e density w/in atoms creates brief polarity & attracts adjacent atom for short time

Question 20

Define mixtures. Describe mixture in the human body.

Answer 20

physically blended but not chemically combined e.g. body fluids
-most mixtures in body consist of chemicals dissolves/suspended in H2O

Question 21

Describe chemical bonds of water and list it’s properties (don’t add property defs)

Answer 21

Has polar bonds covalent bonds and v-shaped molecules (bond gives properties)
-Solvency
-Cohesion
-Adhesion
-Chemical reactivity
-Thermal stability

Question 22

Describe solvency as a property of water (hydrophobic and hydrophilic definitions alongside)

Answer 22

ability to dissolve into other chemicals
-Hydrophilic-substance dissolves H2O
Molecules must be polarized /charged
-Hydrophobic-substance does not dissolve H2O
Molecules are non-polar/neutral

Question 23

Describe adhesion in the case of water

Answer 23

tendency of different molecules to bond to each other
-H2O adheres to large membranes reducing friction around organs

Question 24

Describe cohesion in relation to water

Answer 24

force of attraction between molecules
-H2O cohesive because of H bonds

Question 25

Describe chemical reactivity in relation to water

Answer 25

ability to participate in chemical reactions
-H2O ionised into H and OH
-involved in hydrolysis and dehydration synthesis reactions

Question 26

Describe thermal stability in relation to water

Answer 26

helps stabilise internal body temperature
-high heat capacity as H bonds inhibit temp increases by inhibiting molecular motion
-effective coolant

Question 27

define solution. Can they pass through membrane?

Answer 27

particles (solute) mixed with abundant substance (usually H2O) called solvent
-will pass

Question 28

Define colloids. Can they pass through membrane

Answer 28

in body, are often mixtures of protein and H2O
-particles too large to pass through membrane

Question 29

Define suspension. Can they pass through membrane

Answer 29

too large to penetrate selectively permeable membranes
e.g. blood cells in plasma