Today we started with a practice naming quiz. When I went over the answers I also reviewed some naming rules and patterns
Next we prepared for lab – set up lab notebook, did pre-lab problems, etc. We only had about 40 minutes to do the lab and there was so much difficulty in getting equipment found, set-up, etc. that only one group actually managed to get a melting point! So we’ll try again tomorrow!
In the mean time, here are some more details on what is on your test on Monday
no safety questions,
Sig figs and dimesional analysis only as they apply to mole calculation problems
No lewis structures
No organic functional group identification
Ions will be limited to the ones you can predict from the periodic table, transition metals and the BOLDED ones on this ion sheet.
I like all the topics we are studying to fit together in a nice neat package…here is the story for this unit. You could use this as a study guide, even.
How do we know that there are atoms? What evidence did Dalton have?
Law of Definite Proportions
Law of conservation of mass
Part of Dalton’s hypothesis was that atoms combine in whole number ratios. We can experimentally determine the percent by mass, but in order to determine whole number ratios we need….good atomic weights and the mole concept
In order to get good atomic weights we needed to take into consideration the different “flavors” that atoms come in. Various isotopes have different masses so we utilize a weighted average since we don’t just deal with one atom a time (usually).To get average atomic weights we use mass spectrometry (Dalton didn’t have this – I don’t know how they did it!)
Outline how Mass Spectrometry works –
Determine relative abundance of various isotopes and calculate average atomic weight based on spectra
The mole concept was developed because we generally are unable to measure just one atom at a time. The mole was defined such that the mass on the periodic table, not only represented one atom, but also represented the mass in grams of a large collection of atoms. It just so happens that the number of atoms in this collection is …
Now that we have a way of counting atoms by weighing we can determine the whole number ratios in which they combine
Empirical Formula Problem
It turns out that some elements combine in the same proportion, but have different properties: glucose and fructose. Thus, it is necessary to know not just ratios, but the actual number of atoms in the molecule. For this we need the mass spectrometer again.
The molecular ion peak on the spectra gives …
Molecular formula problem
Now we have a way of keeping track of the atoms in each molecule we needed to develop a systematic way of naming them.
Knowing the molecular formula also allows us to understand many of the other chemical and physical properties these molecules have. Many of these properties result from the ratio of one element to another.
Mole ratio problems (How many atoms in 10.o grams of copper (II) carbonate?)
Read the experiment description (scroll down a bit past the theory)
Make a data notebook entry for this.
For procedures: give reference URL and summarize the process
What happens? What is measured?
How is the mass of CO2 used to determine the moles of carbon in the original sample?
How is the mass of water used to determine the moles of H in the original sample?
If you know the mass of the carbon and the mass of the H in the original sample, how do you find the mass and moles of Oxygen?
Data Collection: Do one random compound that has 3 elements. (the random option will allow you to see the formulas to check your work)
No qualitative observations, uncertainty or error prop required
Data Processing Show calculations for empirical and molecular formula
Homework: Work on end of chapter problems (See unit outline. These will be due Monday before your test). Also read sections 2.6 and 2.7 for a refresher on the difference between ionic and covalent bonding (molecules vs. formula units) or watch18 minutes of this video: (a live lecture)
Tonight’s homework: Finish Density lab, review average atomic mass and moles (watch videos) we’ll do practice next class
Review matter concepts (matter web)
Finish Data Collection for Density lab
Homework: Finish density lab error analysis, review moles, average atomic mass – see videos below (keep in mind these videos were done for my chem 1 class at GMHS so some of the things I say like, “you’ll learn in IB chem…” are not accurate!