Chemistry Gas Laws

A student inflates a balloon with helium and then places it in the freezer. The student should expect

the balloon’s volume to decrease

A student measures the pressure and volume of an empty water bottle to be 1.4 atm and 2.3 L. She then decreases the pressure to 0.65 atm. What is the volume?

5.0L

Which of the following would increase the gas pressure of a system?

All of these (Pump in more gas, increase the temperature, reduce the volume)

What is 50 degrees C in Kelvin?

323

Calculate the volume that a 0.323-mol sample of gas will occupy at 265 K and a pressure of 0.900 atm.

7.81L

Pressure is

created by the force of gas particles impacting the walls of the container.

A sample of gas with a volume at 30.0 mL at 25.0C is heated to 50.0C. What is the new volume of the gas?

32.5 mL

What are trends?

Patterns that repeat over time. In chemistry, trends refer to the predictable changes in properties or behaviors of elements across periods and groups in the periodic table.

Atomic Mass

Based on an atoms mass of protons and neutrons. Group: Increases top to bottom. Period: Increases left to right.

Atomic number

Tells you the number of protons and electrons in an atom of the element.

Period: Increases left to right

Group: Increases top to bottom

Atomic Radii

One half the distance between two nuclei

Measured in nanometers

Group: Increases from top to bottom

Period: Decreases Left to right

Ionization Energies

The amount of energy needed to remove an electron from an atom.

Units given in joules

Period: creases left to right

Group: Decreases top to bottom

Electronegativity

Ability of an atom to attract electrons when the atom is in a compound.

Group: Decreases from top to bottom

Period: Increases left to right

Which Element has the smaller atomic radius?

Bromine (yes) or Flourine (no)

Which element has the greatest ionization energy: Aluminum or Chlorine?

Chlorine Cl

Which element has the greatest electronegativity: Nitrogen or Arsenic?

Nitrogen (N)

Which group of the periodic table is composed of inert (not reactive) gases?

noble gases

As you move down a group, atomic radius increases because

you add more and more shells (energy levels)

The atom with the largest atomic radius in group 18 is

Rn

As you move across the periodic table from left to right, the atomic radius decreases since

the number of protons increases, so attraction to electrons increases

(Fr) Francium has the lowest ionization energy in Group 1 because

its 1 valence electron is very far from the nucleus, so little energy is needed to remove it.

Families all have similar

properties

Which has the greatest electronegativity: H or F?

F

As you move across the period table atoms tend to get smaller because, the atoms have more protons.

the atoms have more protons.

The element with the smallest ionization energy in period 6 is

Cs

In an endothermic reaction, energy is

absorbed

Solid to liquid to gas is which reaction?

endothermic

Gas to liquid to solid is which reaction?

exothermic

Ice cubes in your glass of soda melt. Endo or exo?

Exothermic

You freeze juice to make ice pops

exothermic

What type of reaction occurs in a hand warmer

exothermic

When you have Br-Br, what is the polarity?

non polar

When you have H-Cl, what is the polarity?

polar

What does “polar” mean?

A molecule has areas of positive and negative charge

Which end of the water molecule slightly positive charge?

the hydrogen end

If you place a hot object to cool water, what must happen

The thermal energy of water will increase by the same amount that the thermal of the object decreases.

Which statement about the direction of energy flow for a glass of ice water?

Thermal energy flows from the glass to the room

Which energy transfer happens in a solar panel?

Conversion of electromagnetic energy (solar energy) into electrical energy through the photovoltaic effect.