Barium is an element in group 2, period 6 of the periodic table. What does this indicate about its properties?

Question

A: It has 2 valence electrons and is a non-reactive gas.
B: It has 2 valence electrons and is highly reactive.
C: It has 6 valence electrons and is a semimetal.
D: It has 6 valence electrons and is soft and crumbly.

Answer 1

The correct answer is:

B: It has 2 valence electrons and is highly reactive.

Barium, being in group 2 of the periodic table, means it has 2 valence electrons. Elements in this group, known as the alkaline earth metals, are typically highly reactive, especially with water and acidic solutions.

Answer 2

Which element has the same number of valence electrons as bromine (Br)?

• chlorine (CI)
• selenium (Se)
• krypton (Kr)
• potassium (K)

Answer 3

Bromine (Br) is in group 17 of the periodic table, which means it has 7 valence electrons. The element that has the same number of valence electrons as bromine is:

Selenium (Se)

Selenium is in group 16 and shares the same number of total electron shells as bromine (both are in the same period). However, if we strictly consider elements that are of the same group, then the closest element with 7 valence electrons is chlorine (Cl), which is in group 17 just above bromine.

So, the best answer that matches in terms of group and valence electrons in this specific context would be:

Chlorine (Cl).

Answer 4

Why are sodium (Na) and potassium (K) in the same group on the periodic table?
• They are both colorless.
• They have similar atomic weights.
• They have similar reactivity.
• They are both hard and brittle.

Answer 5

Sodium (Na) and potassium (K) are in the same group on the periodic table because:

They have similar reactivity.

Both sodium and potassium are alkali metals (Group 1) and exhibit similar chemical properties, including their reactivity with water and other substances. This is due to their having one valence electron, which makes them highly reactive and allows them to readily lose that electron to form positive ions.

Answer 6

A student cuts some fabric into two pieces. Is this change physical or chemical?
• It is a chemical change because the size changes.
• It is a physical change because the process is reversible.
• It is a chemical change because there is no phase change.
• It is a physical change because there is no reaction.

Answer 7

The correct answer is:

It is a physical change because there is no reaction.

Cutting fabric into two pieces does not alter the chemical composition of the material; it simply changes its physical form or size. Physical changes can typically be reversible, and in this case, the fabric can be sewn back together, though that's not a requirement for classifying it as a physical change.

Answer 8

How are chemical changes different from physical changes?
• They include shifts in the phase of matter.
• They are reversible.
• They involve heat.
• They form new substances.

Answer 9

The correct answer is:

They form new substances.

Chemical changes involve the formation of new substances as a result of a chemical reaction, where the original substances undergo changes in their chemical composition. In contrast, physical changes do not create new substances; instead, they involve changes in physical properties, such as phase (solid, liquid, gas), shape, or size, without altering the chemical composition of the material.

Answer 10

Which phenomenon occurs because of adhesion?
• Two water droplets that touch join to form one larger drop.
• Water droplets stick to a window after a rainstorm.
• Water forms into droplets if you drip water onto a table.
• Soap bubbles form into the shape of a sphere.

Answer 11

The phenomenon that occurs because of adhesion is:

Water droplets stick to a window after a rainstorm.

Adhesion refers to the attraction between different substances, such as water molecules adhering to the glass of the window. In contrast, cohesion refers to the attraction between molecules of the same substance, such as the formation of larger water droplets when two water droplets touch.