Chemistry Test #1 Flashcards
How many valence electrons do elements in group 14 have?
4 valence electrons.
Define valence electrons.
The electrons found on the outermost energy level of an atom and are responsible for determining the atom’s chemical properties.
Transition metals are found in:
Groups 3-12
What are transition metals characterized by?
Their ability to form stable ions with various oxidation states due to the presence of incompletely filled d orbitals.
How many electrons can the p sub level hold?
A maximum of 6 electrons. According to the Pauli exclusion principal, there are three orbitals each capable of accommodating up to 2 electrons.
The F-Block is characterized by….
filling the 4f sub level. The sub level is found within the lanthanide and actinide series and can hold a maximum of 14 electrons.
Elements in group 16 have ____ electrons in their outermost energy level.
6 electrons.
Elements in the D-Block are often referred to as…
transition elements. These element exhibit variable oxidation states and form colorful compounds due to the presence of partially filled d orbitals.
How many electrons can the d Sublevel hold?
A maximum of 10 electrons. (this sub level consists of 5 orbitals, each capable of holding up to 2 electrons)
what block are Lanthanides and Actinides located?
The F-block of the periodic table. (This series of elements are characterized by the filling of the 4f and 5f orbitals)
How many valence electrons do elements in the halogen group typically have?
7 valence electrons.
How does the atomic radius size trend?
The atomic radius increases from top to botton within a group in the periodic table. (this trend occurs because the outermost electrons are in higher energy levels- leading to larger atomic sizes)
The radius of an atom decreases when it…
Loses an electron. (this occurs because the removal of an electron reduces the repulsion between electrons in the outer energy levels, causing the remaining electrons to be pulled closer to the nucleus)
The radius of an atom increases when it…
Gains an electron. (the addition of an electron leads to increased electron-electron repulsion, causing the outermost electrons to occupy a larger volume)
What is ionization energy?
the energy required to remove an electron from an atom
What is the trend in Ionization Energy?
The trend in ionization energy generally increases fro left to right across a period in the periodic table due to increased nuclear charge.
What is the octet rule?
The octet rule states that atoms tend to gain, lose, or share electrons with other atoms to achieve a full octet of valence electron, thereby attaining greater stability.
What is the definition of electronegativity?
Electronegativity a measure of an atoms ability to attract shared electrons in a chemical bond.
Salts with metals are typically formed by elements belonging to which group?
The Alkali metals (alkali metals typically form ionic compounds with nonmetals, resulting the formation of salts.
What properties do metalloids exhibit?
They have properties intermediate between metals and nonmetals, useful in various technological applications.
What characteristic is shared by all noble gases?
They all have full valence electron shells, making noble gases stable and uncreative under normal conditions.
What characteristic group are Magnesium and Calcium in?
Alkaline Earth Metals. These metals are characterized by their reactivity forming basic oxides and hydroxides.
Describe 3 physical properties of liquid nitrogen.
inert, colorless, odorless, noncorrosive, nonflammable, and extremely cold
Explain how liquid nitrogen’s properties arise from tis molecular structure and intermolecular forces.
Nitrogen gas (N2) is diatomic and nonpolar due to its linear molecular structure, resulting in weak intermolecular forces known as London dispersion forces.
What are 3 practical applications of liquid nitrogen in various fields? How do its unique properties make it suitable for these applications?
- Cryopreservation and Cryogenic Stabilization: Liquid nitrogen is used for cryopreserving biological samples, such as eggs, sperm, and animal genetic samples, due to its extremely low temperature and low reactivity
- Cooling Superconductors: Liquid nitrogen is used to cool superconducting materials, such as vacuum pumps and other equipment, due to its very low temperature. This is essential for maintaining the superconducting state of these materials, allowing them to exhibit their unique characteristics
- Cryogenic Machining and Cutting: In industries like manufacturing and aerospace, liquid nitrogen is used for cryogenic machining and cutting of materials like titanium alloy and hardened steel. Its extremely low temperature allows for efficient cooling during the cutting process, reducing tool wear and enabling the processing of difficult-to-machine materials
Outline 3 safety precautions that should be observed when handling liquid nitrogen in a lab or industrial setting. Explain the potential hazards associated with its use and how to mitigate them to ensure safe handling.
- Use Appropriate Personal Protective Equipment (PPE)
- Handle in Well-Ventilated Areas
- Use Only Approved Containers and Equipment
- Use Appropriate Personal Protective Equipment (PPE):
Hazard: Liquid nitrogen is extremely cold and can cause frostbite or cold burns upon contact with skin or eyes
Mitigation: Wear appropriate PPE, such as a full face shield, safety glasses, thermal insulated or leather gloves, long-sleeve shirts, and trousers without cuffs to minimize skin exposure - Handle in Well-Ventilated Areas:
Hazard: Liquid nitrogen can vaporize and displace oxygen, leading to the risk of asphyxiation in poorly ventilated areas
Mitigation: Ensure that all handling of liquid nitrogen is done in well-ventilated areas to prevent the accumulation of nitrogen gas and the reduction of oxygen levels
-Use Only Approved Containers and Equipment:
Hazard: Improper containers or equipment can lead to pressure buildup, explosions, or leaks, causing severe injuries or property damage
Mitigation: Use only approved impact-resistant containers designed for cryogenic service, and never seal liquid nitrogen in a container to prevent pressure buildup and potential explosions
What happens when aluminum is added to hydrochloric acid?
2Al + 6HCl -> 2AlCl_3 + 3H_2
If you have 2 * 10^12 (two trillion) atoms of Aluminum how many atoms of HCl do you need to react, and fully use all the atoms of aluminum?
You would need 3.6132 * 10^24 atoms of HCl
How can you speed up the reaction between aluminum and HCl? (Know a household experiment to investigate factors that affect the rate of the reaction and what you predict will happen if you change the size of aluminum pieces or increase the concentration of HCl. )
To speed up the reaction, increase the surface area of the aluminum, elevate the temperature of the HCl, or stir/agitate the mixture.
Know the Lewis dot structure for the following elements.
Rb, Sr, Ga, Sn
