SNC2D – Chemistry: Chemical Reactions

Subatomic Particles, Atomic Notation, Periodic Table

(p. 184-185)

Subatomic Particles:

Atoms are composed of 3 basic subatomic particles:

Particle Name and Symbol / Charge / Location in Atom
Protons (p+) / Positive / In the nucleus
Neutrons (n°) / Neutral / In the nucleus
Electrons (e-) / Negative / Moving around the nucleus

Atomic Notation:

Atomic notation is a concise, convenient way to give information about the atom of an element.

General Format / Example with Sodium
/ X – element symbol
A – atomic mass (# protons + # neutrons)
Z – atomic number (# protons) / / Na – symbol for sodium
Atomic mass = 23 (# protons + # neutrons = 23)
Atomic number = 11 (# protons = 11)
To find the # of neutrons = Mass # – Atomic #

Examples and Practice:

/ # protons = 17
# electrons = 17
# neutrons = 35 – 17 = 18 / / # protons = 26
# electrons = 26
# neutrons = 56 – 26 = 30
/ # protons = 19
# electrons = 1919
# neutrons = 2039 – 19 = 20 / / # protons = 99
# electrons = 9 9
# neutrons = 10
/ # protons = 47
# electrons = 47
# neutrons = 61

Practice Exercises:

a.  Identify the elements which have the following numbers of protons in the nuclei of their atoms:

8 _O-_oxygen_ / 30 _Zn-_zinc_ / 38 _Sr-strontium / 82 _Pb-_lead_

b.  Write the atomic notation for each of the following atoms:

a)  An atom with 8 protons and 6 neutrons: ____________

b)  An atom with 6 protons and 6 neutrons: ____________

c)  An atom with 1 proton and 0 neutrons: ____________

d)  An atom with 45 neutrons and 35 electrons: _________

c.  Name the element that:

a)  has an atomic number of 7 and a mass number of 14: __nitrogen______

b)  has 10 protons and a mass number of 20: __neon______

c)  has 17 electrons and 17 protons: __chlorine______

d)  has 30 neutrons and a mass number of 56: ___iron______

Teacher Demo

Reactivity of the Group 1 Alkali Metals (Demo)

Metal / Observations (strength of the reaction, gas produced? Etc.)
Lithium / -  heat, bubbles due to gas produced
Sodium / -  Moved around dish, bubbles, more reactive than lithium
Potassium / -  Caught fire, heat, gas produced

The Elements Video

-  tom Lehrer flash video

Alkali metals and myth busters – flash video