Question

Refer to the periodic table inside the front cover and identify (a) the element that is in group 14 and the fourth period (b) one element similar to and one unlike sulfur (c) the alkali metal in the fifth period (d) the halogen element in the sixth period

Short answer

The answers are (a) Germanium (Ge), (b) Selenium (Se) is similar to sulfur and Neon (Ne) is unlike sulfur, (c) Rubidium (Rb), and (d) Astatine (At).

Step-by-step solution

Identify the Element in Group 14 and Fourth Period

Refer to the Periodic Table. Look for Group 14 first, then move to the fourth period in this group. The element is Germanium (Ge).

Identify Elements Similar to and Unlike Sulfur

Elements that are similar are usually in the same group since they share similar chemical properties. Sulfur (S) is in group 16, so an element similar to Sulfur could be Selenium (Se). Elements that are unlike would be in different groups. Thus, an element unlike Sulfur could be Neon (Ne) from group 18.

Identify the Alkali Metal in the Fifth Period

Alkali metals are found in Group 1 of the Periodic Table. The alkali metal in the fifth period is Rubidium (Rb).

Identify the Halogen in the Sixth Period

Halogen elements are found in Group 17 of the Periodic Table. The halogen in the sixth period is Astatine (At).

Key concepts

Group 14

Group 14 on the periodic table is known as the carbon group. It encompasses elements such as carbon (C), silicon (Si), germanium (Ge), tin (Sn), and lead (Pb). These elements are found in the same vertical column, which means they share similar properties. However, they still have distinct characteristics due to their different periods.

One of the key properties of Group 14 elements is their ability to form four covalent bonds. Carbon, being the most well-known member, can form chains and complex structures due to its bonding versatility. This is the basis for organic chemistry.

As you move down the group, from carbon to lead, elements become more metallic in nature. This is because the metallic character increases down a group as atomic size and electron shielding increase, making it easier for these elements to lose electrons and exhibit metallic properties. For instance, carbon is a non-metal, silicon and germanium are metalloids, while tin and lead are metals.

Alkali Metal

Alkali metals are located in Group 1 of the periodic table. They include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). These elements are known for being highly reactive due to their single valence electron, which they tend to lose easily to form positive ions. This results in the alkali metals being very good conductors of electricity.

In the fifth period, the alkali metal is rubidium (Rb). Rubidium, like other alkali metals, reacts vigorously with water, producing hydrogen gas and forming strong bases, such as rubidium hydroxide (RbOH).

Alkali metals have low melting points compared to most other metals. They are also very soft, with some soft enough to be cut with a knife. Due to their reactivity, especially with water, they are not found freely in nature but rather always in compound form.

Halogen

Halogens are the elements in Group 17 of the periodic table. This group includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). Halogens are known for their high reactivity, particularly with alkali and alkaline earth metals, due to having seven electrons in their outer shell. This makes them eager to gain an additional electron to achieve a stable noble gas configuration.

The sixth period halogen is astatine (At). Unlike some of the more common halogens, astatine is a rare and radioactive element. Its chemical properties are not as well-studied due to its scarcity and radioactivity. However, it is expected to follow the trend of increasing atomic size and decreasing electronegativity moving down the group.

Halogens can form salts when they react with metals, a characteristic that gives the group its name (from Greek "halos" meaning salt and "gen" meaning born or produced). They are also known for their ability to form acids, such as hydrochloric acid (HCl), when combined with hydrogen.

Chemical Properties

The periodic table is organized in a way that reveals patterns in the chemical properties of elements. Elements in the same group, or columns, often have similar chemical behaviors because they have the same number of electrons in their outer shell.

For instance, alkali metals in Group 1 are highly reactive and tend to form +1 ions due to their single valence electron. Their reactivity increases down the group, making cesium and francium highly reactive compared to lithium and sodium.

On the other hand, halogens in Group 17 are also reactive but tend to form -1 ions as they seek to gain an electron to fill their valence shell. Their reactivity decreases as you move down the group due to an increase in atomic size and electron shielding, which makes electron gain less favorable.

Elements in Group 14, meanwhile, can show varied chemical properties. Carbon is unique due to its ability to form a vast number of compounds, and its chemistry forms the backbone of organic chemistry. Further down the group, elements like tin and lead exhibit more metallic characteristics.