Atoms, Elements and Isotopes Flashcards
What is the size of an atom?
- 0.1 Nanometers
What is an atom made up of?
- Electrons
- Protons
- Neutrons
What is the overall charge of an atom?
- Zero
- Neutral
What is the charge of a proton?
- +1
- Positive
What is the charge of a neutron?
- 0
- Neutral
What is the charge of an electron?
- -1
- Negative
What is the mass of a neutron?
- ‘1’
What is the mass of an electron?
- ‘Very small’
What is the mass of a proton?
- ‘1’
What is an element made up of?
- One type of atom
What does the atomic mass number represent?
- Amount of protons
What does the mass number represent?
- Amount of protons and neutrons
How do you calculate the amount of electrons?
- There are the same amount of protons as neutrons
- Protons = Electrons
- This does not apply for ions
What is the max amount of electrons that can be held in each shell of an atom?
- 2,8,8
- First shell 2
- Rest 8
- When one fills up, move to the next
Sodium has 11 electrons.
How would you draw an atom for sodium?
- Circle in the middle for nucleus and protons
- 3 shells
- First shell 2 electrons
- Second shell 8 electrons
- Third shell 1 electron
How can you tell which is the atomic mass number and which is the mass number?
- The atomic mass number is always smaller
How do you calculate the amount of neutrons?
- Mass number - atomic mass number
Oxygen has the mass number of 16 and atomic mass of 8.
How many protons, electrons and neutrons does it have?
- Electrons = 8 ( 8 = 8 )
- Protons = 8 ( atomic mass )
- Neutrons = 8 ( 16 - 8 )
What is an ion?
- An atom with a positive or negative charge
- e.g H+ Na+ Ca2+ F− O2−
How does an atom have a positive or negative charge?
- Losing an electron = Positive
- Gaining an electron = Negative
Remember; an electron has -1 charge, if you gain a -1, the number decreases, if you get rid of a -1, the number increases.
Magnesium has 12 electrons.
It gains one electron, what charge is it?
- Negative
Fluorine has 9 electrons.
It loses one electron, what charge is it?
- Positive
What is an isotope?
- Different amount of neutrons of the same element
- e.g Carbon-12 Carbon-13
What is the equation for relative atomic mass?
- Relative atomic mass = isotope abundance x isotope mass number / 100
Lithium-4 has an abundance of 20% and Lithium-5 has an abundance of 80%.
What is the relative atomic mass?
- ( 4 x 20 ) x ( 5 x 80 )
- 80 x 400
- 32000
- 32000 / 100
- 320 relative atomic mass
Before the discovery of electrons, what did scientists think atoms were?
- Small solid spheres
What was the first model of the atom?
- Plum Pudding
- Spherical cloud of positive charge
- Electrons spread throughout
Who created the Plum Pudding model?
- John Dalton
Why was the Plum Pudding model incorrect?
- Neutrons existed
What is the Nuclear model?
- A positive charged nucleus
- Surrounded by scattered electrons
How was the Nuclear model discovered?
- Fired positively charged alpha particles thin gold foil
- If the Plum Pudding model were correct, all alpha particles would pass through
- Some particles reflected
- Nucleus reflected alpha particles theory
Who created the Nuclear model?
- Ernest Rutherford and Ernest Marsden
Why was the Nuclear model incorrect?
- Without electron shells, the atom would collapse
What is the Bohr’s Nuclear model?
- The Nuclear model with electron shells
- Electrons orbit the nucleus
Who created Bohr’s Nuclear model?
- Neils Bohr
What are the differences between the Plum Pudding model and Nuclear model?
- Existence of a nucleus
