atomic structure, isotopes and formulae Flashcards
What was stated in Dalton’s atomic theory?
- Atoms are tiny particles made of elements
- Atoms cannot be divided
- All the atoms in an element are the same
- Atoms of one element are different to those of other elements
What is the relative mass of a proton
1
Define molecular ions
Covalently bonded atoms that lose or gain electrons
How do you calculate the number of neutrons?
mass number - atomic number
What is the charge of the ion when electrons are gained?
Negative
Define relative isotopic mass
The mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon-12
Explain how to calculate the empirical formula
- Divide amount of each element by mr
- Divide answers by smallest obtained value
- If it is a decimal divide by suitable number to get a whole number
Which letter represents the mass number?
A
Explain the current model of the atom
- Protons and neutrons are found in the nucleus
- Electrons orbit in shells
- Most the atom is empty space between the nucleus and the electrons
What were Rutherfords proposals 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 atom’s volume is space between the nucleus and the electrons
- Overall positive and negative charges must balance
How is the mass number calculated?
number of protons + 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 the 4 elements that don’t form ions and why?
- The elements: beryllium, boron, carbon and silicon
- Require a lot off energy to transfer outer shell electrons
What letter represents the atomic number of an atom?
Z
The relative isotopic mass is the same as which number?
Mass number
What does the atomic number tell us about an element?
The number of protons in an atom
What is the charge of a proton?
1+
What is the relative mass of an electron
1/2000
How is the periodic group number related to the number of electrons?
Represents the number of electrons in an atoms outer shell
Define ions
Charged particles that are formed when an atom loses or gains electrons
How to calculate the relative molecular mass and the relative formula mass?
Add up the relative atomic masses of each of the atom making up the molecule/formula
Define relative atomic mass
The weighted mean mass of an atom of an element compared with 1/12th of the mass of 1 atom of carbon-12
What did Thompson discover about electrons?
- They have a negative charge
- They can be deflected by magnets and electric fields
- They have a small mass
What is the relative mass of a neutron
1
Define an empirical formula
Simplest whole number ratio of atoms of each element present in a compound
What is the charge of an electron?
-1
Explain the plum pudding model
Atoms are made up of negative electrons moving around in a sea of positive charge
Define an isotope
Atoms of the same element with different number of neutrons and masses
Which two particles make up most of the atom’s mass?
Protons and neutrons
How does a mass spectrometer work?
- The ions are vaporised
- The atoms are ionised by bombarding it with electrons to knock off its own electrons to create a positive ion which create a narrow beam
- The ions are accelerated via a negatively charged accelerating plate so they have the same kinetic energy
- Ions are deflected by the magnetic field by their mass/charge ratio
- The beam of ions passing through the machine is detected electrically, a signal is amplified
and recorded
What two assumptions are made when calculating mass number?
- Contribution of the electron is neglected
2. Mass of proton and neutron is taken as 1.0 u
Do metals gain or lose electrons?
Lose electrons to form positive ions
What are the uses of mass spectrometry?
- Identifying unknown compounds
- Finding relative abundance of each isotope in an element
- Determining structural information
What is the location of electrons in an atom
The orbitals
What particle has the same mass as a proton?
A neutron
The formula of an ammonium ion
NH4+
The formula of a sulfate ion
SO4 2-
The formula of a zinc ion
Zn2+
The formula of a silver ion
Ag+
The formula of a carbonate ion
CO3 2-
The formula of a nitrate ion
NO3 -
The formula of a hydroxide ion
OH-
