Elements, Compounds and Mixtures Test - 2

An atom is the smallest particle of any element that still retains the characteristics of that element. A piece of an element that we are able to see or handle is made of many, many atoms and all atoms are the same. They all have the same number of protons.

Stainless steel is a metal alloy, made up of steel mixed with elements such as chromium, nickel, molybdenum, silicon, aluminum, and carbon. Iron mixed with carbon to produce steel is the main component of stainless steel. Chromium is added to make it resistant to rust.

Elements, which are composed of a single type of atom, contain different numbers of protons. Molecules are formed when two or more atoms bond together. If molecules contain atoms of different elements, that substance is known as a compound.

An element is a pure substance that cannot be broken down into simpler substances by chemical or physical means. Each element has unique physical and chemical properties.

Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air.  It is the fifth most abundant element in Earth's crust and the third most abundant metal, after iron and aluminium.

Igneous rocks are formed from lava or magma. Magma is molten rock that is underground and lava is molten rock that erupts out on the surface. The two main types of igneous rocks are plutonic rocks and volcanic rocks. Plutonic rocks are formed when magma cools and solidifies underground.

In total, 118 elements have been identified. The first 94 occur naturally on Earth, and the remaining 24 are synthetic elements. There are 80 elements that have at least one stable isotope and 38 that have exclusively radionuclides, which decay over time into other elements.

H₂O a.k.a water is a COMPOUND because water has 2 different molecules which are chemically bonded. H₂O can't be a mixture because it's bonded chemically and can't be separated into H₂ and O by physical means. It can't be an element because H₂O a.k.a water is made of atoms of different types (Hydrogen & Oxygen).

Chemists ordinarily work with weighable quantities of elements and compounds. For example, in the iron-sulfur equation the symbol Fe represents 55.845 grams of iron, S represents 32.066 grams of sulfur, and FeS represents 87.911 grams of iron sulfide.

Sediment in rivers gets deposited as the river slows down. Larger, heavier particles like pebbles and sand are deposited first, whilst the lighter silt and clay only settle if the water is almost still.

Hydrogen is seen as an element because, it is the simple and ample element in the world.

The reason for considering HYDROGEN as a chemical element because it is the lightest element and it is colorless, tasteless, and odorless.

Iron is described as an element because it is a pure substance. A pure substance is where the atoms are similar and cannot be divided into smaller.