chem u5

What does the Periodic Law state about elements arranged by atomic numbers?

When elements are arranged in order of increasing atomic numbers, their physical and chemical properties show a periodic pattern.

What is periodicity in the context of the periodic table?

Periodicity refers to regularly repeating patterns or trends in the chemical and physical properties of the elements.

How does the atomic radius change when moving down a group in the Periodic Table?

The atomic radius increases going down a group because each element has one more principal energy level filled with electrons.

What happens to the atomic radius when moving from left to right across a period?

The atomic radius decreases going from left to right across a period due to the increasing positive charge of the nucleus.

What do Lewis dot diagrams represent?

Lewis dot diagrams show the number of valence electrons for an element.

What is the octet rule in the context of covalent compounds?

The octet rule states that atoms in a molecule share electrons to gain a filled valence level, generally aiming for eight electrons.

What represents a single covalent bond in a Lewis diagram?

Each shared pair of electrons in a Lewis diagram represents a single covalent bond.

What does collision theory state about chemical reactions?

Collision theory states that particles must collide to break chemical bonds and react.

What is an effective collision?

An effective collision occurs when particles collide at the proper orientation and with sufficient energy to react.

What is the difference between exothermic and endothermic reactions?

Exothermic reactions release energy (−ΔH), while endothermic reactions absorb energy (+ΔH).

What does the term 'molarity' refer to in chemistry?

Molarity refers to the number of moles of a solute per liter of solution.

What is a synthesis reaction? Provide a general formula.

A synthesis reaction occurs when two or more substances combine to form a single product. General formula: A + B → AB.

What is a decomposition reaction? Provide a general formula.

A decomposition reaction is when a compound breaks down into two or more simpler substances. General formula: AB → A + B.

What does percent yield measure in a chemical reaction?

Percent yield measures the efficiency of a reaction by comparing the actual yield to the theoretical yield.

What are functional groups in organic chemistry?

Functional groups are groups of atoms besides carbon and hydrogen in hydrocarbons that are responsible for the chemical properties of the hydrocarbon.