Editing Period 4 element (section)

==d-block elements==
===Scandium===
[[File:Scandium sublimed dendritic and 1cm3 cube.jpg|frameless|left|upright=0.3]]
[[Scandium]] (Sc) is the third element in the period, and is the first [[transition metal]] in the periodic table. Scandium is quite common in nature, but difficult to isolate because its chemistry mirrors that of the other [[rare earth element|rare earth]] compounds quite closely. Scandium has very few commercial applications, the major exception being [[aluminium]] [[alloy]]s.

===Titanium===
[[File:Titan-crystal bar.JPG|frameless|left|upright=0.3]]
[[Titanium]] (Ti) is an element in [[group 4 element|group&nbsp;4]]. Titanium is both one of the least dense metals and one of the strongest and most corrosion-resistant.  As such, it has many applications, especially in alloys with other elements, such as iron. It is commonly used in [[airplane]]s, [[golf club]]s, and other objects that must be strong, but lightweight.

===Vanadium===
[[File:Vanadium etched.jpg|frameless|left|upright=0.24]]
[[Vanadium]] (V) is an element in [[group 5 element|group&nbsp;5]]. Vanadium is never found in pure form in nature, but is commonly found in compounds. Vanadium is similar to titanium in many ways, such as being very corrosion-resistant, however, unlike titanium, it oxidizes in air even at room temperature. All vanadium compounds have at least some level of toxicity, with some of them being extremely toxic.

===Chromium===
[[File:Chromium crystals and 1cm3 cube.jpg|frameless|left|upright=0.3]]
[[Chromium]] (Cr) is an element in [[group 6 element|group&nbsp;6]]. Chromium is, like titanium and vanadium before it, extremely resistant to corrosion, and is indeed one of the main components of [[stainless steel]]. Chromium also has many colorful compounds, and as such is very commonly used in pigments, such as [[chrome green]].

===Manganese===
[[File:Manganese electrolytic and 1cm3 cube.jpg|frameless|left|upright=0.3]]
[[Manganese]] (Mn) is an element in [[group 7 element|group&nbsp;7]]. Manganese is often found in combination with iron. Manganese, like chromium before it, is an important component in [[stainless steel]], preventing the iron from rusting. Manganese is also often used in pigments, again like chromium. Manganese is also poisonous; if enough is inhaled, it can cause irreversible neurological damage.

===Iron===
[[File:Iron electrolytic and 1cm3 cube.jpg|frameless|left|upright=0.3]]
[[Iron]] (Fe) is an element in [[group 8 element|group&nbsp;8]]. Iron is [[Abundance of elements on Earth|the most common on Earth]] among elements of the period, and probably the most well-known of them. It is the principal component of [[steel]]. [[Iron-56]] has the lowest energy density of any isotope of any element, meaning that it is the most massive element that can be produced in [[supergiant]] [[star]]s. Iron also has some applications in the human body; [[hemoglobin]] is partly iron.

===Cobalt===
[[File:Kobalt electrolytic and 1cm3 cube.jpg|frameless|left|upright=0.3]]
[[Cobalt]] (Co) is an element in [[group 9 element|group&nbsp;9]]. Cobalt is commonly used in pigments, as many compounds of cobalt are blue in color. Cobalt is also a core component of many magnetic and high-strength alloys. The only stable isotope, [[cobalt-59]], is an important component of [[vitamin B-12]], while [[cobalt-60]] is a component of nuclear fallout and can be dangerous in large enough quantities due to its radioactivity.

===Nickel===
[[File:Nickel chunk.jpg|frameless|left|upright=0.2]]
[[Nickel]] (Ni) is an element in [[group 10 element|group&nbsp;10]]. Nickel is rare in the Earth's crust, mainly due to the fact that it reacts with oxygen in the air, with most of the nickel on Earth coming from [[nickel iron meteorite]]s. However, nickel is very abundant in the [[Earth's core]]; along with iron it is one of the two main components. Nickel is an important component of stainless steel, and in many [[superalloys]].

===Copper===
[[File:NatCopper.jpg|frameless|left|upright=0.24]]
[[Copper]] (Cu) is an element in [[group 11 element|group&nbsp;11]]. Copper is one of the few metals that is not white or gray in color, the only{{citation needed|date=August 2019}} others being [[gold]], [[osmium]] and [[caesium]]. Copper has been used by humans for thousands of years to provide a reddish tint{{clarification needed|date=August 2019|reason=In elemental form? As a powder, sheets, or how in the hell at all? Compounds of copper are indeed turquoise or cyan.}} to many objects, and is even an essential nutrient to humans, although too much is poisonous. Copper is also commonly used as a wood preservative or [[fungicide]]s.

===Zinc===
[[File:Zinc fragment sublimed and 1cm3 cube.jpg|frameless|left|upright=0.3]]
[[Zinc]] (Zn) is an element in [[group 12 element|group&nbsp;12]]. Zinc is one of the main components of [[brass]], being used since the 10th century BCE. Zinc is also incredibly important to humans; almost 2 billion people in the world suffer from zinc deficiency.  However, too much zinc can cause copper deficiency. Zinc is often used in batteries, aptly named [[carbon-zinc batteries]], and is important in many platings, as zinc is very corrosion resistant.