# How to draw a (Bohr) model of an atom

## Presentation on theme: "How to draw a (Bohr) model of an atom"— Presentation transcript:

How to draw a (Bohr) model of an atom

Step 1: find the element on the periodic table… Let’s try Sodium (Na)

Step 2: Determine the atomic number (smaller of the 2 numbers)… So, for Sodium (Na), the atomic # is 11. The atomic # tells us 2 things: Number of protons (= 11) Number of electrons (= 11)

Step 3: Determine the atomic mass (bigger of the 2 numbers) & round to the nearest whole number…
So, for Sodium (Na), the atomic mass is 22.99, but rounded to the nearest whole number it’s 23. atomic mass = # of protons + # of neutrons

Step 4: Calculate the number of neutrons…
atomic mass = # of protons + # of neutrons So… 23 = 11 + # of neutrons Which is the same as… = # of neutrons Therefore… 12 = # of neutrons

Now… to draw your Bohr model of the atom...
Sodium (Na) Atomic number: 11 Atomic mass: 23 # of protons: 11 # of neutrons: 12 # of electrons: 11 First, draw your nucleus with the protons and neutrons…. Na 11 p+ 12 n0

Now… to draw your Bohr model of the atom...
Sodium (Na) Atomic number: 11 Atomic mass: 23 # of protons: 11 # of neutrons: 12 # of electrons: 11 Second, draw your first energy level, which can hold up to 2 electrons maximum…. Na 11 p+ 12 n0 2 e-

Now… to draw your Bohr model of the atom...
Sodium (Na) Atomic number: 11 Atomic mass: 23 # of protons: 11 # of neutrons: 12 # of electrons: 11 You still have 9 electrons left… Draw a second energy level, which can hold up to 8 electrons maximum…. Na 11 p+ 12 n0 2 e- 8 e-

Now… to draw your Bohr model of the atom...
Sodium (Na) Atomic number: 11 Atomic mass: 23 # of protons: 11 # of neutrons: 12 # of electrons: 11 You still have 1 electron left… Draw a third energy level, which can hold up to 8 electrons maximum…. But, you only have 1 electron left, so this energy level will not be full… Na 11 p+ 12 n0 2 e- 8 e- 1 e-