Chemistry Module 2 - Chapter 2 Flashcards
What was stated in Dalton’s atomic theory? (4)
- Atoms are tiny particles made of elements.
- Atoms cannot be divided.
- All the atoms in a element are the same.
- Atoms of one element are different to those of other elements.
What did Thompson discover about electrons? (3)
- They have a negative charge.
- They can be deflected by magnets and electric fields.
- They have a very small mass.
Explain the plum pudding model.
Atoms are made up of negative electrons moving around in a sea of positive charge.
What were Rutherford’s proposal after the gold leaf experiment?
- Most of the mass and positive charge of the atom are in the nucleus.
- Electrons orbit the nucleus.
- Most of the atom’s volume is the space between the nucleus and the electrons.
- Overall positive and negative charges must balance.
Explain the current model of the atom. (5)
- Protons and neutrons are found in the nucleus.
- Electrons orbit in shells.
- Nucleus is tiny compared to the total volume of atom.
- Most of atom’s mass is in the nucleus.
- Most of the atom is empty space between the nucleus and the electrons.
What is the charge of the proton?
1+
What is the charge of the electron?
1-
What is the charge of the neutron?
0
What is the relative mass of the proton?
1
What is the relative mass of the neutron?
1
What is the relative mass of the electron?
1/1840
What two particles make up most of the atom’s mass?
Protons + Neutrons
What letter is used to represent the atomic number of an atom?
Z
What does the atomic number tell about an element?
Atomic number = number of protons in an atom.
What letter represents the mass number?
A
How is the mass number calculated?
Mass Number = number of protons + number of neutrons
How do you calculate the number of neutrons?
Number of neutrons = Mass number - Atomic Number
Define istope
Different forms of the same elements, with the same number of protons but a different number of neutrons.
Why do different isotopes of the same element react in the same way?
- Neutrons have no impact on the chemical reactivity.
- Reactions involve electrons, isotopes have the same number of electrons in the same arrangement.
What are ions?
Charged particles that is formed when an atom loses of gains electrons.
What is the charge of the ion when electrons are gained or lost?
Gained = negative
Lost = positive
What are positive and negative ions called?
Positive ions = cations
Negative ions = anions
What is the unit used to measure atomic masses called?
Unified atomic mass unit = u