07&09/10: Isotopes and Ar

• Chemistry
• Secondary Education

Pres_Template

CHEMISTRY 9

17 - Electron configuration

draw a Bohr's diagram of an atom of an element.

write the electron configuration of an element.

electron shell

nucleus

electron

Bohr's diagram of an atom

Bohr's diagram of an atom

Electron shells

• the allowed energies of electrons in atoms
• electrons fill these shells (or levels), starting with the one closest to the nucleus

Electron shells

• the allowed energies of electrons in atoms
• electrons fill these shells (or levels), starting with the one closest to the nucleus

Electron shells

• the allowed energies of electrons in atoms
• electrons fill these shells (or levels), starting with the one closest to the nucleus

Electron shells

• the allowed energies of electrons in atoms
• electrons fill these shells (or levels), starting with the one closest to the nucleus

The atomic theory of the arrangement of electrons (Bohr's Model)

• a model of the atom in which electrons can only occupy certain shells (or energy levels) moving outwards from the nucleus of the atom

Electron shells

• the allowed energies of electrons in atoms
• electrons fill these shells (or levels), starting with the one closest to the nucleus

The atomic theory of the arrangement of electrons (Bohr's Model)

• a model of the atom in which electrons can only occupy certain shells (or energy levels) moving outwards from the nucleus of the atom

Electron shells

• the allowed energies of electrons in atoms
• electrons fill these shells (or levels), starting with the one closest to the nucleus

The atomic theory of the arrangement of electrons (Bohr's Model)

• a model of the atom in which electrons can only occupy certain shells (or energy levels) moving outwards from the nucleus of the atom

How do we use Bohr's diagram to show the electron configuration of an atom of an element?

Sample 1: Draw the Bohr's diagram of Helium

How do we use Bohr's diagram to show the electron configuration of an atom of an element?

Bohr's diagram

Electron configuration:

How do we use Bohr's diagram to show the electron configuration of an atom of an element?

Sample 2: Draw the Bohr's diagram of Lithium

Bohr's diagram

Electron configuration:

Electron configuration:

draw a Bohr's diagram of an atom of an element.

I can draw the Bohr's diagram of an atom of an element.

Yes, I can confidently draw it.

Yes, I can but need more practice.

No, I lack confidence so I need more practice or ask help from my teacher.

Choose ONE and do it on your whiteboard.

WE DO it together!

Collaborative Group Work

TEAM ________

Draw the Bohr's diagram of your chosen element.

Bohr's diagram

Electron configuration:

Electron configuration:

Choose ONE and do it in your notebooks.

YOU DO it together!

Collaborative Pair Work

write the electron configuration of an element.

I can write the electron configuration of an element.

Yes, I can confidently write it.

Yes, I can but need more practice.

No, I lack confidence so I need more practice or ask help from my teacher.

Pres_Template

CHEMISTRY 9

16 - Isotopes

• GOOD MORNING! Perhaps you can greet Teacher Russel and your classmates, too?
• Where will you put your notebook, workbook, and pen or pencil?
• Have you joined our LessonUp slides?
• Have you checked any announcements or missing work on our Google Classroom?
• Are you seated in your assigned chair?

Let's make our day right!

state the 

A_r equation.

use the A_r equation to calculate elements' relative atomic mass.

carbon-14

carbon-12

carbon-13

Isotopes are atoms
of the same element,
the same p_ _ _ _ _ number,
but a different n_ _ _ _ _ _ number
(proton + neutron).

Isotopic mass or atomic mass of the isotope

(mass of the isotope)

atomic number or proton number

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass (A_r)

• the average mass of naturally occurring atoms of an element on a scale where the carbon-12 atom has a mass of exactly 12 units

Relative atomic mass

• the unit called the amu (u) is used
• relative atomic mass unit (amu) = 1/12th the mass of a carbon-12 atom

What is the equation for relative atomic mass, a.k.a Ar?

What is the equation for relative atomic mass, a.k.a Ar?

state the 

A_r equation.

I CAN state the A_r equation.

Yes, I can confidently state it.

Yes, I can but need more practice.

No, I lack confidence so I need more practice or ask help from my teacher.

What is the equation for relative atomic mass, a.k.a Ar?

How do we use the equation for relative atomic mass, a.k.a Ar?

Sample question 1:

• Lithium has two naturally occurring isotopes: 6Li (7% abundance) and 7Li (93% abundance). Calculate the relative atomic mass of lithium.

Thought-process

How do we use the equation for relative atomic mass, a.k.a Ar?

Sample question 2:

• Boron has two naturally occurring isotopes with the natural abundances shown in the table below:

Thought-process

How do we use the equation for relative atomic mass, a.k.a Ar?

Question 1:

• Chromium has four naturally occurring isotopes, and their masses and natural abundances are shown in the table below. Calculate the relative atomic mass of chromium to two decimal places.

Question 2:

• Mass spectroscopic analysis of a sample of magnesium gave the following results. Calculate the relative atomic mass, Ar, of this sample of magnesium to two decimal places.

WE DO it together!

Collaborative Group Work

Question 1:

• Chromium has four naturally occurring isotopes, and their masses and natural abundances are shown in the table below. Calculate the relative atomic mass of chromium to two decimal places.

Question 2:

• Mass spectroscopic analysis of a sample of magnesium gave the following results. Calculate the relative atomic mass, Ar, of this sample of magnesium to two decimal places.

WE DO it together!

Collaborative Group Work

use the Ar equation to calculate elements' relative atomic mass.

I CAN use the Ar equation to calculate elements' relative atomic mass.

Yes, I can confidently use it.

Yes, I can but need more practice.

No, I lack confidence so I need more practice or ask help from my teacher.

YOU DO it together!

Collaborative Pair Work

Open your notebook.

• Look for the pasted piece of paper with a table related to relative atomic mass.
• Work with your seatmate. Help each other calculate the Ar of the isotopes. CHOOSE TWO ONLY.
• Please raise your hand if you need any help or if you want me to provide feedback about your work.

• Accomplish the reflection sheet.
• Share your goal with your seatmate.

• Accomplish the reflection sheet.
• Share your goal with your seatmate.

Choose one and do it in your notebook.

YOU DO it alone!

Independent Practice

Write the electron configuration of Neon, Argon, and Krypton. 

Q1: Do they have similar properties?

Q2: What causes this similarity?

Q3: What pattern do you see in the number of electrons?

Q4: How are they used in daily life?

Characteristics of isotopes