Lecture 1

Question 1

Nucleus includes: (2)

Answer 1

• Neutron

- Proton

Question 2

Electrons (4)

Answer 2

• occupies large space
• occupies in shells
• inner shell has max 2 e-
• outer electrons, aka outermost shells

Question 3

Why is carbon 12.03?

Answer 3

• because of isotopes

Question 4

What is isotopes?

Answer 4

same # of electrons, different neutrons

Question 5

What are isotopes used for?

Answer 5

• imagining, radiocarbon dating

Question 6

Radiocarbon dating

Answer 6

use to determine the dead, fossils and how long these bones last for

Question 7

Mass number (He 4 or 2)

Answer 7

• top # (4)

- # of protons + neutrons

Question 8

atomic number

Answer 8

• number of protons

Question 9

All life depends on what in the atmosphere?

Answer 9

• carbon dioxide

Question 10

Archeology

Answer 10

• the study of human activity through the recovery and analysis of material culture
• takes bones and grind them, see how much C14 are in these bones.

Question 11

If bones have the same amount of C14 as in the atmosphere, what does that mean?

Answer 11

• recent bone

once u die, the exchange of CO2 stops, C14 starts to decay, gets less and less overtime

Question 12

What causes the formation of chemical bonds?

Answer 12

To link atoms tgt, to form chemical bonds, only electrons are important.

Question 13

What elements mostly made up our body? (4)

Answer 13

• hydrogen
• carbon
• nitrogen
• oxygen

Question 14

Periodic table (group)

Answer 14

same amount of e- in the outer most shell, meaning that they are similar chemistry

Question 15

Rows (period)

Answer 15

all the amount in the same rows are roughly the same size, because of the same # of shells

Question 16

Three types of bond

Answer 16

• covalent bond

- ionic bond

Question 17

Covalent bond (3)

Answer 17

1. A covalent bond is made of 2 electrons
2. These 2 electrons are shared, i.e. one electron comes from each atom
3. Atoms can form bonds until their outermost shell is filled

Question 18

What is so special about central atom?

Answer 18

95% probability of where e- are

Question 19

What is nonpolar covalent bond?

Answer 19

Electrons are shown to be superimposed
on the bond to indicate that they are
halfway between the two atoms, shared
equally

Question 20

Polar covalent bonds

Answer 20

Electrons are not shared equally
(O is more electronegative than
H), so partial charges exist on
the O and H atoms
Polar = shared unequally, e- spend more time on the oxygen

Question 21

Trends of electronegativity

Answer 21

The higher the electronegativity, the stronger the attraction

Question 22

Valence electron

Answer 22

number of unpaired electrons

Question 23

What is so special about hydrogen bond? (2)

Answer 23

• A meniscus forms where water meets a solid surface,
  as a result of two forces.
• high surface tension
• in trees, water can rise up to the top because of hydrogen bond, force that push the water up (evaporation) coz of hydrogen bond
• (a) In ice, water molecules form a crystal lattice.
• (b) In liquid water, no
  crystal lattice forms.
• (c) Liquid water is denser than ice. As a result,
  ice floats.

Question 24

Adhesion: Water

Answer 24

Water molecules that adhere to the glass resist the downward pull of cohesion

Question 25

Cohesion: Water

Answer 25

Water molecules at the surface experience a net downward pull from hydrogen bonds with water molecules below