Unit 2 Chapter 1

Question 1

octet rule

Answer 1

tendency to prefer to have 8 electrons in the valence shell

Question 2

empirical knowledge

Answer 2

obtained through results of experiments

Question 3

theoretical knowledge

Answer 3

obtained through observations

Question 4

*An attempt to use familiar ideas
to describe unfamiliar things in a
visual way.
*It can be changed as new
information is collected.

Answer 4

scientific model

Question 5

Democritus VS Aristotle

Answer 5

Things are made of atoms VS 4 earth elements

Question 6

Dalton’s Billiard Ball Model

Answer 6

THOUGHT atoms were indivisible (False)
Atoms of the same element have identical properties. ✅

3. Atoms of different elements combine
   in constant ratios to form compounds
   (Law of Constant composition)✅
4. Chemical reactions involve the
   rearrangement of atoms; no new
   atoms are created or destroyed (Law
   of Conservation of Mass) ✅

Question 7

Thomson

Answer 7

Empirical Evidence:
*As an electric current passed through a
gas, it gave off rays of negatively
charged particles.
* However, the gas was surprisingly
uncharged (neutral).
Conclusions:
*A particle smaller than an atom had to
exist.
– negative charges (e-s) came from
within the atom

ATOM WAS DIVISIBLE!

THOUGHT *There must be positively charged
particles in the atom, but he could never
find them.

Question 8

Plum pudding

Answer 8

Thomson

FOUND ELECTRONS !!!

Question 9

involved firing a stream
of tiny positively
charged alpha particles
at a thin sheet of gold
foil
* expected positive
charges to be spread
out evenly and
not enough to stop an
alpha particle

Answer 9

Rutherford’s Gold foil experiment

Empirical Evidence:
*Most of the positively charged alpha particles passed
straight through the gold foil.
*Some of the positively charged alpha particles
bounce away from the gold foil as if they
had hit something solid.

Question 10

Rutherford’s Gold Foil Experiment Conclusion

Answer 10

Conclusions:
*Gold atoms in the sheet were mostly empty space.
– Atoms were not a pudding filled with a positively
charged material (Thompson).

*An atom has a small, dense, positively charged
center (i.e. NUCLEUS) that repelled the
positively charged alpha particles.

.: Nucleus is tiny compared to the atom as a whole.

HE FOUND PROTONS

Question 11

_______ Model by rutherford

Answer 11

all of an atom’s positively charged
particles were
contained in the
nucleus.
* Negatively charged
particles were
scattered outside the
nucleus around the
atom’s edge.

Question 12

Student of Rutherford - Chadwick

Answer 12

modified
Rutherford’s Mostly
Empty Space model
* atoms have a third
subatomic particle
being

NEUTRONS
in the nucleus

Question 13

Bohr’s Planetary Atom Model

Answer 13

Electrons orbit the nucleus in circular
paths of fixed energy (ENERGY LEVELS).
* Electrons can jump (i.e.
transition) from energy level
to energy level.
* The higher the energy level, the
further it is away from the nucleus.
* PHOTONS are bundles of light
energy that that are emitted by
electrons as they go from higher
energy levels to lower energy levels.

Question 14

ground state + excited state

Answer 14

Ground state is the lowest possible
energy level an
electron can be at.

excited state is an energy level
higher than the
ground state.

Question 15

P.E.N

Answer 15

subatomic particles

Question 16

Atoms of the same
element that have
a different #s of neutrons
yet they look, act
and react the
same.

Answer 16

isotopes

Question 17

device to identify isotopes

Answer 17

mass spectrometer

Question 18

Dobereiner

Answer 18

noticed a similarity
among the physical &
chemical properties
within several groups of
3 elements

• LAW OF TRIADS
  – middle element had a
  mass about halfway
  between the atomic
  masses of the other two

Question 19

Newlands

Answer 19

arranged all known
elements in order of
increasing atomic
mass

• LAW OF OCTAVES
  – repeating physical
  and chemical
  properties every 8
  elements

Question 20

Mendeleev

Answer 20

grouped elements with
similar properties in the
same column
– left blank spaces to add
elements

• PERIODIC LAW
  – elements arranged by
  increasing atomic mass
  show a periodic
  recurrence of properties
  at regular intervals

Question 21

Modern periodic law

Answer 21

When the internal
structure of atoms was
discovered,
Mendeleev’s Periodic
Law was revised
– elements arranged by
increasing atomic #
show a periodic
recurrence of properties
at regular intervals

Question 22

sits atop group 1, but
it is not a member of
that family
* class of its own
* gas at room
temperature
* 1 p+ and 1 e-

in its
only energy level
* only 2 e-

to fill up its

valence shell

Answer 22

hydrogen

Question 23

group 1
* 1 valence e-
* most reactive
metals
– with halogens and
oxygen
– violently with water
to make a base
* soft, silver, solids
@ SATP

Answer 23

alkali metals family

Question 24

alkaline earth metals family

Answer 24

group 2
* 2 valence e-s
* react slowly with
water
* solid @ SATP
* react with air to form
oxides
* react with H+ to form
hydrides (except Be)

Question 25

groups 3 – 12
* strong, hard metals,
high melting points
* good conductors
* some form
multivalent ions
* variable reactivity
– many react with
oxygen to make
oxides
– some react with
acids

Answer 25

transition metals

Question 26

7 metalloids along the staircase divides
metals on left from non-metal on right.

Answer 26

B, Si, Ge, As, Sb, Te, Po

Question 27

halogens

Answer 27

group 17 non-metals
* 7 valence e-s
* extremely reactive
with hydrogen and
metals
* solid, liquid or gas
* dull, do not conduct
electricity

Question 28

noble gases

Answer 28

group 18 non-
metals

• full valence shell
• extremely un-
  reactive (stable)
• low melting &
  boiling points

Question 29

atomic # 57 - 70
* rare earth
metals
* belong to the 6th
period

Answer 29

lanthanides

Question 30

Actinides

Answer 30

atomic # 89 – 102
* belong to the 7th period
* include elements
which are radioactive
and synthetic
* atomic #93+
(transuranic
elements) are
synthetic

Question 31

w/in a period, chemical reactivity is high in group 1,
lower towards the middle of P.T., maximum in group
17, and lowest in group 18.
* w/in a group, the chemical reactivity of metals
increase moving down while non-metals decrease
moving down.

Question 32

Lewis Diagrams

Answer 32

Lewis diagrams represent valence
electrons involved in bonding
–A chemical symbol represents the
nucleus and core electrons (not
involved in bonding).
–Dots around the symbol represent
valence electrons.

Question 33

1. Write the element symbol.
2. Draw dots, one for each valence electron
3. Dots should be spread over 4 sides

• It does not matter what side the dots are placed, but
  do not start to pair dots until there is one on each side

Answer 33

The number of valence electrons is equal to the
group number (for groups 1-3, 14-18), with
one exception. Which element is it?
Helium has 2 valence electrons in group 18

Question 34

atomic radius

Answer 34

• the distance from the nucleus to just beyond the outermost electrons (valence electrons). In a diatomic molecule (such as nitrogen, N 2 , or oxygen, 0 2 ), the atomic radius is defined as the distance between the two nuclei, divided by 2

Question 35

Every electron in an atom experiences a force of attraction toward the nucleus

Answer 35

effective nuclear charge

Question 36

This occurs because the electrons of the inner levels ___ the outer electrons from the full charge of the nucleus. As a result, the outer electrons are not as strongly attracted by the nucleus, resulting in a larger atomic radius.

Answer 36

electron shielding

Question 37

ionic radius

Answer 37

a measurement of the size of an ion, usually expressed in picometres (pm); the distance from the centre of an ion to the outermost electrons

Question 38

representative elements

Answer 38

group 1, 2, 13-18 pg 31