SNC2D Grade 10 Science - academic Chemistry review: grade 9.
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Transcript of SNC2D Grade 10 Science - academic Chemistry review: grade 9.
Properties of matter A physical property is a characteristic of a substance that can be
observed or measured without changing the substance’s composition (i.e. ice is still water). Some physical properties:
1 – colour2 – texture (fine, coarse, smooth, etc)3 – odour (odourless, spicy, sharp, etc)4 – luster (shiny, dull, vitreous, etc)5 – taste (sweet, sour, bitter, etc)6 – hardness (measure of resistance of been scratched. A harder material will scratch a softer one. Diamond will scratch glass. Nail will scratch a chalk)7 – Solubility (ability of a substance to dissolve in a solvent like water. Salt is soluble and pepper is insoluble)8 – Viscosity (how easily a liquid flows. Maple syrup is more viscous (“thicker”) than water9 – state (whether is solid, liquid, or gas at room temperature)10 – melting and boiling points (temperature which substances change state. Liquid water changes to vapour at 100 0C and become solid ice at 0oC)
Physical Properties of Matter
Properties of matter
A description / statement of whether or not a substance reacts with another substance to form a new compound is a chemical property of matter. Examples below:
Chemical Properties of Matter
1 – Combustibility: ability of a substance to react with oxygen to produce carbon dioxide, water, and energy when exposed to flame. Gasoline is combustible (= flammable or inflammable). Water is non-flammable.
2 – Reaction with acid: ability to react with acid. Limestone (chalk) reacts with acid producing bubbles of gas.
Each row in the periodic table is known as Periods. The columns, which consist of elements having similar chemical properties, are known as Groups or Families.
The periodic table has 7 periods and 18 families.
METALS NONMETALS METALLOIDS
Shine, usually grey (except gold and copper), and solid (except mercury). They are good conductors of heat & electricity. Can be hammered into sheets without breaking.
Dull, different colours , solid, gases, or liquid. Not good conductors. Easily broken.
An element having both metallic and nonmetallic properties. They are usually good semiconductors
(web.buddyproject.org/.../web017/ images/periodic%20table.JPG)
SUBATOMIC PARTICLESSUBATOMIC PARTICLES
Particle
proton
neutron
electron e-
Charge
positive charge
negative charge
no charge
1
1
0(almost 2000
times lighter than proton or
neutron)
Mass
p+
n
Atomic Number
Is the number of protons in an atom.
by association, it’s also the number of electrons, since atoms are neutral (charge zero)
Practice questions
State the number of protons for atoms of each of the following:1. Nitrogen a) 5 protons b) 7 protons c) 14 protons
2. Sulfur a) 32 protons b) 16 protons c) 6 protons
3. Bariuma) 137 protons b) 81 protons c) 56 protons
Answers
State the number of protons for atoms of each of the following:1. Nitrogen b) 7 protons 2. Sulfur
b) 16 protons
3. Bariumc) 56 protons
Atomic number and atomic mass in the Periodic Table
11Na
22.99
Atomic Number
Symbol
Atomic Mass
Protons =11
Electrons =11
Protons +neutrons =22.9
(round off the number to 23)
Neutrons =23-11=12
Atomic number = number of protons in nucleus
Mass number = number of protons + number of neutrons
= atomic number + number of neutrons
Cl3517
Mass Number
Atomic NumberElement Symbol
Standard atomic notation
17 protons17 electrons18 neutrons (= 35 -17)
Subatomic Particles in Some Atoms
16 31 65
O P Zn8 15 30
8 p+ 15 p+ 30 p+
8 n 16 n 35 n8 e- 15 e- 30 e-
Protons and neutrons: nucleus
Electrons The circles are NOT orbits. The electrons are NOT moving around the nucleus along the circles, like planets around the sun. It is impossible to know how an electron is actually moving in an atom .
Instead, the circles represents regions called orbitals (or shells) with different energy levels. The two electrons on the circle closest to the nucleus have the lowest energy and the eight electrons on the next circle have a higher energy.
2-8-8 rule*
Building in which next floor up can only be filled if the lower floor is filled
* The maximum number of electrons that can occupy each shell has been determined for the 20 first elements
ELECTRON ORBITALSELECTRON ORBITALS
Electrons are arranged in Energy Shells/
or Valence Shells around the nucleus of
an atom.• first shell a maximum of 2 electrons
• second shell a maximum of 8
electrons
• third shell a maximum of 8
electrons
BOHR - RUTHERFORD DIAGRAMSBOHR - RUTHERFORD DIAGRAMS
Bohr – Rutherford diagrams are simple drawings
that show the numbers and locations of protons,
neutrons and electrons in an atom (or ion).
Nitrogen 7p+
7n0oo o
oo
o
o
N7
14
BOHR - RUTHERFORD DIAGRAMSBOHR - RUTHERFORD DIAGRAMS
Draw the Bohr - Rutherford diagrams for the atoms of the following elements: Oxygen and Chlorine
O Cl8 17
16 35a) b)
8 p+
8n0
o
o
o
o
o
o
o17 p+18 no
o
o
o
o
o
o
oo
oo o
o
o o
o
oo
SUMMARYSUMMARY
1. The Atomic Number of an atom = number of
protons in the nucleus.
2. The Mass Number of an atom = number of
Protons + Neutrons in the nucleus.
Atomic Mass = mass of protons and neutrons and electrons of the atom
3. The number of Protons = Number of Electrons.
4. Electrons are located around the nucleus in energy shells.
5. Each shell can only carry a set number of electrons.
ATOMIC STRUCTURE MODELSATOMIC STRUCTURE MODELS
There are several ways to represent the
atomic structure of an element or compound:
2. Electronic Configuration
1. Bohr - Rutherford Diagrams
ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION
With electronic configuration elements are
represented numerically by the number of
electrons in their shells and number of shells. For
example;
NNitrogen
7
142 in 1st shell
5 in 2nd shell
configuration = 2 , 5
2 + 5 = 7
ELECTRONIC CONFIGURATIONELECTRONIC CONFIGURATION
Write the electronic configuration for the following elements;
Ca O
Cl Si
Na20
40
11
23
8
17
16
35
14
28
B11
5
a) b) c)
d) e) f)
2,8,8,2 2,8,1
2,8,7 2,8,4 2,3
2,6
Ionic Compound (metal + non metal)
Write down the name of the first element;
Write down the name of second element and add “IDE”.
e.g. Magnesium + oxygen magnesium oxide
BaCl2 barium chloride
K2O potassium oxide