Quantitative Vs Qualitative Data
This type of data describes qualities or characteristics and is usually descriptive
Qualitative data
This scientist is credited with creating the first widely recognized periodic table
Dmitri Mendeleev
Lewis Dot Structures show these electrons around an atom
Valence electrons
How many significant figures are in the number 1200 (with no decimal shown)?
2 significant figures (the trailing zeros are not significant without a decimal)
Isotopes differ in this part of the atom
The number of neutrons
Quantitative data is always expressed in this form
Numerical form (numbers, measurements)
Elements in the same column or group of the periodic table share this common characteristic
Same number of valence electrons and similar chemical properties
How many valence electrons does oxygen have in its Lewis dot structure?
6 valence electrons
True or False: all nonzero digits are significant
True
True or False: Isotopes of the same element have the same number of protons
True
Name one example of qualitative data in a chemistry experiment
Example: color change, texture, smell or appearance
As you move from left to right across a period, the atomic radius generally does this:
Decreases (atomic radius gets smaller)
Draw the Lewis Dot Structure for a chlorine atom (draw this on your whiteboard)
Cl with seven dots arranged around the symbol to represent valence electrons
How many significant figures are in 0.00789?
3 significant figures
Explain the difference between atomic mass and mass number.
Mass number is the total number of protons and neutrons in a single atom; atomic mass is the weighted average of all isotopes’ masses.
When measuring the temperature of a solution, this type of data is recorded
Quantitative data (e.g., temperature in C)
This trend describes the ability of an atom to attract electrons in a chemical bond
Electronegativity
Draw the Lewis Dot Structure for both Hydrogen and Oxygen
Hydrogen has 1 valence electron and oxygen has 6
True or False: If the digit to the right of the last significant figure is less than 5, do not round up.
True
Why do isotopes of the same element have nearly identical chemical properties?
Because they have the same number of protons and electrons, which determine chemical behavior
Explain why quantitative data is important for scientific experiments
Quantitative data allows precise measurement and comparison, making experiments reproducible and results reliable.
Explain the significance of Mendeleev leaving gaps in his periodic table
He predicted the existence and properties of undiscovered elements by leaving gaps.
How many valence electrons does Nitrogen have?
5 valence electrons
How many significant figures are in this number?: 60002
5 significant figures (zeros sandwiched between two sig figs are significant)
If an element has two isotopes, one with mass 35 amu (75% abundance) and one with mass 37 amu (25% abundance), what is its average atomic mass?
(35×0.75)+(37×0.25)=26.25+9.25 = 35.5 amu