Atoms Elements And Compounds

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  1. Elements And Compounds Chart
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Differences in Properties

Atoms

An atom is the smallest part of an element that can exist. An element is a substance made up of one type of atom while a compound is a substance formed by the chemical union of two or more. Atoms, Elements, and Compounds What’s the difference? Atoms  Atoms are the basic building blocks of all matter  Atoms are made up of 3 subatomic particles:  Protons – positively charged  Neutrons – no charge  Electrons – negatively charged 3.

Elements are distinguished by their name, symbol, atomic number, melting point, boiling point, density and ionization energies. In the Periodic Table, elements are arranged according to their atomic number and they are grouped according to similar chemical properties and are depicted by their symbols.

  • Atomic number – the atomic number is denoted by the letter Z and is the number of protons present in the nucleus of the atom of element. For e.g. carbon has 6 protons in its nucleus and for Carbon, Z = 6. Number of protons is also indicative of electric charge or number of electrons present in the nucleus which determines chemical properties of the element.
  • Atomic Mass – the letter A indicates the atomic mass of the element which is the total number of protons and neutrons in the nucleus of an atom of the element. Isotopes of the same elements differ in their atomic masses.
  • Isotopes – isotopes of an element have the same number of protons in their nucleus but differ in the number of neutrons. Naturally occurring elements have more than one stable isotope. Thus isotopes have similar chemical properties (due to same number of protons) but different nuclear properties (due to different number of neutrons). For e.g. carbon has three isotopes, Carbon - 12, Carbon -13 and Carbon - 14.
  • Allotropes – atoms of an element can form bonds with each other in more than one way leading to difference in their chemical properties. For e.g. carbon binds in a tetrahedron to form diamond and layers of hexagons of carbon forms graphite.

Elements, Compounds, and Mixtures Test- Study Guide. Do you know the difference between an element and a compound? The difference between an element and a compound is that an element is a substance made of same type of atoms, whereas a compound is made of different elements in definite proportions. Elements and compounds. Those molecules which are made from only one type of atom are called ELEMENTS. Those molecules which are made up of different types of atoms are called COMPOUNDS, such as the molecule of water. Oxygen (O2), element made up of 2 atoms of oxygen. All known elements are arranged on a chart called the Periodic Table of Elements. A compound is a substance made from two or more different elements that have been chemically joined. Some examples of compounds are water (H 2 O), table salt (NaCl), table sugar (C 12 H 22 O 11) and chalk (CaCO 3).

Compounds are composed of different elements in a fixed proportion. For example, 1 atom of sodium (Na) combines with 1 atom of chlorine (Cl) to form one molecule of sodium chloride (NaCl) compound.The elements in a compound do not always retain their original properties and cannot be separated by physical means. The combining of elements is facilitated by their valency. Valency is defined as the number of hydrogen atoms required that can combine with an atom of the element forming the compound. Most compounds can exist as solids (low enough temperatures) and can be decomposed by the application of heat. Sometimes foreign elements are trapped inside crystal structure of compounds giving them a non homogeneous structure. Compounds are depicted by their chemical formula which follows the Hill system wherein carbon atoms are listed first, followed by hydrogen atoms after which elements are listed in alphabetical order.

Visualizing the Differences

This picture shows the differences between elements and compounds at an atomic level. Elements have only 1 type of atoms; compounds have more than 1. Elements and compounds are both substances; they differ from mixtures where different substances mix together but not via atomic bonds.

A visualization for the differences between elements, compounds and mixtures, both homogenous and heterogenous.

History of Elements and Compounds

Elements were initially used as a reference to any state of matter like liquid, gas, air, solid etc. Indian, Japanese and Greek traditions refer to five elements namely, air, water, earth, fire and aether. Aristotle conceptualized a new fifth element called 'quintessence' - which apparently formed the heavens. As research continued, many eminent scientists paved way for the current understanding and description of elements. Among them, work of Robert Boyle, Antoine Lavoisier, Dmitri Mendeleev are particularly notable. Lavoisier was the first to make a list of chemical elements and Mendeleev was the first to arrange elements according to their atomic number in the Periodic Table. The most current definition of an element is awarded by the studies carried out by Henry Moseley which states that the atomic number of an atom is expressed physically by its nuclear charge.

Before the 1800s the usage of term compound could also mean a mixture. It was in the 19th century that meaning of a compound could be distinguished from a mixture. Alchemists like Joseph Louis Proust, Dalton and Berthollet and their studies on various compounds have given modern chemistry the current definition of compound. Proust’s work demonstrated to the world of chemistry that compounds were made constant composition of respective elements.

CAS Number

Every chemical substance is identified by its unique numerical identifier – the CAS (chemical abstracts service) number. Hence every chemical compound and element has a CAS number. This makes database searches for elements and compounds more convenient.

References

Atomic Theory

Atomic theory first got discovered by scientists who each had different theories. The scientist known as Dalton was the one who had suggested “that matter is made up of atoms”, which was then found as true. Thomson said that ” atoms contain negatively charged particles” which we now call electrons; that was also found later as true. The scientist Rutherford discovered that “the nucleus and ti’s subatomic particles” he thought that the nucleus was made up of positively charged particles. Later known as protons and particles with nob charge were later called neutrons. Bohr then came along and said that “electrons are located in shells which are found around the nucleus”. With all of there discoveries the atomic theory was studied and created.

The Atom

The difference between atoms and molecules are that molecules can gain or lose one or more electrons, while atoms combine to form molecules.

Electrons: are found in the shells, and have a negative charge.

Protons: are found in the nucleus, and have a positive charge.

Neutrons: are found in the nucleus, and have no/neutral charge.

The atomic number on the periodic table of elements represents the amount of protons are in the nucleus. The atomic mass is the mass of the element. Groups are horizontal, and they represent the same properties. Families are vertical and they represent the same number of valence electrons.

Atoms elements and compounds h2so4

The differences between metals, non-metals, and metalloids,are metals are shiny,conductors, and have high density. Non-metals are dull, poor conductors and low density. Metalloids can be shiny or dull, and can conduct better than non-metals but not as well as metals.

Alkali Metals

All the alkali metals react vigorously or explosively with cold water, producing an aqueous solution of the strongly basic alkali metal hydroxide and releasing hydrogen gas.This reaction becomes more vigorous going down the group: lithium reacts steadily with effervescence, but sodium and potassium can ignite and rubidium and caesium sink in water and generate hydrogen gas so rapidly that shock waves form in the water that may shatter glass containers When an alkali metal is dropped into water, it produces an explosion, of which there are two separate stages. The metal reacts with the water first, breaking the hydrogen bonds in the water and producing hydrogen gas; this takes place faster for the more reactive heavier alkali metals. Second, the heat generated by the first part of the reaction often ignites the hydrogen gas, causing it to burn explosively into the surrounding air. This secondary hydrogen gas explosion produces the visible flame above the bowl of water, lake or other body of water, not the initial reaction of the metal with water (which tends to happen mostly under water).

Alkaline Earth Metals

The alkaline earth metals all react with the halogens to form ionic halides, such as calcium chloride as well as reacting with oxygen to form oxides such as strontium oxide. Calcium, strontium, and barium react with water to produce hydrogen gas and their respective hydroxides.

Halogens

Fluorine reacts vigorously with water to produce oxygen and hydrogen fluoride Dissolved chlorine reacts to form hydrochloric acid a solution that can be used as a disinfectant or bleach. Bomine slowly reacts to form hydrogen bromide and hypobromous acid. Iodine However, iodine will form an aqueous solution in the presence of iodide ion, such as by addition of potassium iodide because the triiodideion is formed.

Noble Gases

The noble gases are usually inert, because their electron shells are full. The further away an electron is the higher its energy and the less of a hold the protons have one it. If a highly electro-negative element comes in contact with a noble gas in high heat, the noble gas can lose an electron. The noble gas becomes a cation. The cation noble gas is free to from a ionic bond with a anion.

Elements

A substance consisting of atoms which all have the same number of protons (the same atomic number). Elements are chemically the simplest substances and hence cannot be broken down further using chemical methods. Elements can only be changed into other elements using nuclear methods. A chemical element is a substance that cannot be broken down by chemical means. Elements are defined by the number of protons they possess. Examples of Elements include:copper, cesium, iron, neon

Compounds

A compound is a chemical species that is formed when two or more atoms join together chemically, with covalent or ionicbonds. Also Known As: molecule, though sometimes distinctions are made between the types of bonds in molecules (covalent) and compounds (ionic)

An atom that has an equal number of protons and electrons isn’t positive or negative, it has no charge. If that atom gains or loses electrons it may become a cation, an ion with a positive charge, or an anion, an ion with a negative charge. Chemists use a very simple way to represent ions in chemical reactions. Remember some common polyatomic ions amd you can figure out the symbols for ions just using the periodic table of elements.

Atoms

An atom is the defining structure of an element. Elemental atoms differ from each other by the number of protons in their nucleus. For example, one way to tell oxygen atoms from nitrogen atoms would be to count the number of protons each atom has. Oxygen will have eight where nitrogen will have seven. Stable atoms have the same number of electrons as the number of protons. These electrons form orbitals around the nucleus and cause much of the chemical properties of the element. When an atom’s outermost orbital gains or loses electrons (also known as valence electrons), the atom forms an ion.

Ions: Ions are atoms or molecules that have gained or lost one or more of their valence electrons and have a net positive or negative charge.

Elements And Compounds Chart

Naming

Non-metals & Metals

Sodium bromide — NaBr
Magnesium oxide — MgO
Zinc fluoride — ZnF2

  • Multivalent Metals

Iron (III) oxide — Fe2O3
Tin (II) fluoride — SnF2
Copper (I) chloride — CuCl

  • Polyatomic Ions

Sodium bicarbonate — NaHCO3
Calcium nitrate — Ca(NO3)2
Ammonium hydroxide — NH4OH
Lithium nitrate — Li2Cr2O7

Formula to name

  • Non-metals & Metals

CaCl2 — Calcium chloride
ZnS — Zinc sulphide
Na3N — Sodium nitride

CompoundsH2so4
  • Multivalent Metals

PbO2 — Lead (IV) oxide
SnH4 — Tin (IV) hydride
CrS — Chromium (II) sulphide

  • Polyatomic Ions

Atoms Elements And Compounds H2so4

Pb(CIO3)2 — Lead (II) chlorate
H2SO4 — Hydrogen sulphate
Fe2(SO4)3 — Iron (III) sulphate
Cu3(PO4)2 — Copper (II) phosphate

Properties of Matter

Mass: The amount of matter within an object.
Volume: The amount of space an object takes up.
Density: How much mass in a specific volume an object has.
State: What state an object is in; liquid, solid, or gas.
Colour: The colour of an object.
Melting Point: The temperature where a solid turns into a liquid.
Boiling Point: The temperature where a liquid turns into a gas.
Conductivitiy: The ability of an object to let heat or electricity flow.

Physical & Chemical Changes

Physical and chemical changes are different in what results from each.

Physical Changes

  • Melting
  • Ripping
  • Cutting
  • Grinding
  • Tearing
  • Dissolving

Chemical Changes

Atoms Elements And Compounds Powerpoint

Atoms elements and compounds crossword answers
  • Colour change
  • Heat
  • Light
  • Sound
  • Bubbles

State Change & the Kinetic Molecular Theory

Matter exists in three states, solid, liquid, and gas.

Solid: The particles are very tightly packed, and they have no space to move. They vibrate in place.
Liquid: The particles have a bit more space to move, so they slide past each other.
Gas: The particles have a lot of space to move, and they move freely.


Atoms Elements And Compounds Worksheet