U1 - Module 4: Determining Composition Flashcards
What causes the differences between substances?
Differences in the composition and structure of their particles
What are the three steps of Mass Spectrometry?
- Convert particles into ions.
- Use a magnetic field to separate ions by their mass.
- Obtain a mass/charge ratio.
What is the common charge of mass spectrometry?
+1
What makes up most of the size of an atom?
The outer electron cloud.
What makes up most of the mass of an atom?
The inner nucleus made of protons and neutrons.
What is most of an atom considered?
Empty space
What happens to an atom’s charge when it gains an electron?
It becomes -1
What happens to an atom’s charge when it loses an electron?
It becomes +1
Ions
Charged particles
Atomic Number
The number of protons in the nucleus of an element
Atomic Mass
The number of protons and neutrons
How do you know the number of electrons?
Same as # of protons
- unless there is a present charge
What is m/z?
Mass-charge ratio
What do the peaks in mass spectrum represent?
The abundances of particles of the particular mass.
What causes the presence of multiple peaks in a mass spectrometry graph?
Isotopes
Isotope
When the number of neutrons in an element differs, causing different masses.
Why do molecules turn into isotopes during mass spectrometry?
The process is very hard on the molecules and causes fragments of them to break apart.
What does the largest mass recorded on a mass spectrometry indicate?
The molecular mass of the original molecule.
What is the first thing to look for when analyzing a mass spectrometry graph?
The molecular ion peak (largest mass)
Particle Composition
The type and number of atoms of each type of particle.
What does elemental analysis help find?
The percentage of each element present in the substance.
What are the 4 steps of conducting an elemental analysis?
- Convert relative % to g of the element.
- Convert the grams to moles
- Divide all amounts by the smallest low amount
= Mole ratio - Create the empirical formula using the mole ratio
Empirical Formula
The simplest whole number ratio of atoms present in a compound
Molecular Formula
The ACTUAL number of atoms in a molecule
