Which elements exist as molecules

Can this be true? Name any three elements found in the gaseous phase. Below are the names of three types of animals which we keep as pets or farm. We have to build shelters for them. Write down the name of the shelter next to each animal and describe it briefly. Look at the following molecule, H2O.

How many molecules of sulphuric acid are there in: 5H2SO4? The elements of Group 2 are known as…. The elements of Group 0 8 or 18 are known as Use the model key and draw the model for each of the molecules given. Which spectroscopic technique is most useful for determining pathways for energy flow in molecules? Are the following molecules polar or non-polar?

One exception is mercury Hg , which is a liquid at room temperature Fig. The elements in Group 1, including lithium Li , sodium Na, Fig. These metallic Group 1 elements have similar reactive properties. In Fig 2. Nonmetals are poor conductors of heat and electricity; they are not lustrous and exist in nature as solids, liquids, or gases.

When solid, non-metals tend to be brittle, such as sulfur, which flakes apart rather than bending like a metal would Fig. The elements in Group 17, including fluorine F 2 , chlorine Cl 2 , Fig. The nonmetals in Group 17 are all diatomic two atoms in their elemental form and have similar reactive properties. There are other organizational features of the periodic table.

Most periods have the first element of the period in Group 1 and the last element in Group An exception is the first period. Sometimes hydrogen H is placed in Group 17, above fluorine F , because it has similar properties to the nonmetals in that group; for example, in its elemental state hydrogen exists as a diatomic gas, H2.

Sometimes hydrogen is placed in both Groups 1 and Groups of elements have similar properties. The properties of some groups are so unique or important that the groups are referred to by special names. The elements in this group are called the noble gases. Noble gases seldom react with other elements. Noble gases have many uses, for example, they are used in neon signs Fig 2. Group 1 is often referred to as the alkali metals, Group 2 as the alkaline earth metals, and Group 17 as the halogens.

The two groups that are pulled out on the bottom of the periodic table in rows are called the lanthanide rare earth series top row and the actinide series bottom row. This document may be freely reproduced and distributed for non-profit educational purposes. Skip to main content. Search form Search. Join The Community Request new password.

Main menu About this Site Table of Contents. Atoms, Molecules, and Compounds. NGSS Performance Expectations: HS-PS Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms. The content and activity in this topic will work towards building an understanding of the structure of atoms and how elements are organized on the periodic table. Chemical Structures The properties of elements and compounds are determined by their structures.

Electrostatic Forces Electrostatic forces hold atoms in molecules. Determine how charged matter interacts. Properties of metals and nonmetals Metals Nonmetals Physical Properties Good conductor of heat and electricity Poor conductor of heat and electricity Malleable - can be beaten or deformed without cracking; pliable Brittle Ductile - can be made into wire Non-ductile Lustrous Not lustrous, may be opaque or transparent Solid at room temperature except Hg and a few other metals that are liquid at or near room temperature Solid, liquid, or gas at room temperature Chemical Properties Usually have valence electrons Usually have valence electrons Tend to lose valence electrons Tend to gain electrons.

Other Organizational Features of the Periodic Table There are other organizational features of the periodic table. Begin the name with the element name of the first element. If there is more than one atom of this element in the molecular formula, use a numerical prefix to indicate the number of atoms, as listed in Table 3. Do not use the prefix mono- if there is only one atom of the first element.

Let us see how these steps work for a molecule whose molecular formula is SO 2 , which has one sulfur atom and two oxygen atoms—this completes step 1. According to step 2, we start with the name of the first element—sulfur.

Now for step 3, we combine the numerical prefix di- see Table 3. Bringing these two words together, we have the unique name for this compound—sulfur dioxide. Why all this trouble? There is another common compound consisting of sulfur and oxygen whose molecular formula is SO 3 , so the compounds need to be distinguished.

SO 3 has three oxygen atoms in it, so it is a different compound with different chemical and physical properties. The system of chemical nomenclature is designed to give this compound its own unique name. Its name, if you go through all the steps, is sulfur trioxide. Different compounds have different names.

In some cases, when a prefix ends in a or o and the element name begins with o we drop the a or o on the prefix. So we see monoxide or pentoxide rather than monooxide or pentaoxide in molecule names.

One great thing about this system is that it works both ways. From the name of a compound, you should be able to determine its molecular formula. Simply list the element symbols, with a numerical subscript if there is more than one atom of that element, in the order of the name we do not use a subscript 1 if there is only one atom of the element present; 1 is implied.

From the name nitrogen trichloride , you should be able to get NCl 3 as the formula for this molecule. From the name diphosphorus pentoxide , you should be able to get the formula P 2 O 5 note the numerical prefix on the first element, indicating there is more than one atom of phosphorus in the formula. Some simple molecules have common names that we use as part of the formal system of chemical nomenclature.

For example, H 2 O is given the name water , not dihydrogen monoxide. Molecular Elements There are many substances that exist as two or more atoms connected together so strongly that they behave as a single particle.

If each green ball represents a sulfur atom, then the diagram on the left represents an S 8 molecule. The molecule on the right shows that one form of elemental phosphorus exists, as a four-atom molecule.

Ionic Compounds The elements in the periodic table are divided into specific groupings; the metals, the non-metals, the semi-metals, and so on. Molecular Compounds Compounds that are composed of only non-metals or semi-metals with non-metals will display covalent bonding and will be classified as molecular compounds.

PCl 3 is made up of two nonmetals, so it is a molecular compound. LiBr is made up of lithium, a metal, and bromine, a nonmetal, so it is an ionic compound. P 4 is a substance that is made up of four atoms of the same element, so it is a molecular element. The formula for oxygen gas is O 2 so it is a molecular element.