Chemistry Atoms

Development of the atom

• Dalton theory says that all matter is made of atoms. All atom of a given element are identical in mass/properties
• Compounds are formed by combining two or more different atoms.
• Chemical reaction is a rearrangement of a atoms.

Development of the atom

• J.J. Thomson discovered the electrons by experimenting with a cathode ray tube. He demonstrated that cathode rays were negatively charged. He also made the plum pudding model.

Development of the atom

• Rutherford's invented the gold foil experiment in which he demonstrated that the atom has a tiny, heavy nucleus.
• Designed an experiment to use the alpha particles emitted by a radioactive element as probes to the unseen world of atomic structures.

Development of the atom

• The atomic theory, which holds that matter is composed of tiny, indivisible particles in constant motion, was proposed in the 5th cent.

Atomic Structure

• Electrons are the smallest of the three particles that make up atoms. They are found in shells or orbitals that surround the nucleus of an atoms.
• Protons and neutrons are found in the nucleus. They grouped together in the center of the atom.

Atomic Structure

• Protons are positively charged
• Electrons are neutrally charged
• Neutrons are negatively charged
• Neutrons carry no charge (they are neutral)

Atomic Structure

• The unit of mass is called the Atomic Mass Unit (amu).
• Protons and neutrons have almost the same mass, while the electrons is approximately 2,000 times lighter. They carry charges of equal magnitude, but opposite charge. They are held together closely in the center of the atom.

Atomic Structure

• Neutrons carry no charge because they are neutral.
• It is also the structure of an atom, that is made up of a positively charged nucleus surrounded and neutralized by negatively charged electrons revolving in orbits at varying distances from the nucleus.

Protons, Neutrons, and Electrons

• Protons is a subatomic particle with a positive electric charge of +1e elementary charge and mass slightly less than that of a neutron.
• The neutron is a subatomic particle, with no net electric charge and a mass slightly larger than that of a proton. The nucleus consists of Z protons, where Z is called the atomic number, and N neutrons, where N is a neutron number.

Protons, Neutrons, and Electrons

• Protons and neutrons, each with masses of approximately one atomic mass unit, are collectively referred to as "nucleons". One or more protons are present in the nucleus of every atom. There are a necessary part of the nucleus. The word proton is Greek form for "first", and this name was given to the hydrogen nucleus Ernest Rutherford in 1920.

Protons, Neutrons, and Electrons

• It's an essential to the production of nuclear power. In the decade after the neutron was discovered in 1932, neutrons were used to persuade many different type of nuclear transmutations.
• With the discovery of produce of nuclear fission in 1938, it was quickly realized that, if a fission event produced neutrons, each of these neutrons might cause further fission events, etc., in a cascade known as a nuclear chain reaction.

Protons, Neutrons, and Electrons

• The electron is a subatomic particle, symbol e or B, with a negative elementary electric charge.
• Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no known components or substructure. They have a mass that is approximately 1/1836 that of the proton. Quantum mechanical properties of the electron include an intrinsic angular momentum (spin) of a half-integer value, expressed in units of the reduced Planck constant.

Protons, Neutrons, and Electrons

• With the discovery of produce of nuclear fission in 1938, it was quickly realized that, if a fission event produced neutrons, each of these neutrons might cause further fission events, etc., in a cascade known as a nuclear chain reaction.

Compound formulas

• A compound is a substance which is formed when two or more chemical elements are chemically bonded.
• There are two types of chemical bonds and they are covalent bonds and ionic bonds.

Compound formulas

• A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using a single line of chemical element symbols, numbers, and sometimes also other symbols, such as parenthesis, dashes, brackets, commas and plus (+) an minus (-) signs.

Compound formulas

• A chemical formula is not a chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. It can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than are chemical names and structural formulas.

Compound formulas

• The simplest types of chemical formulas are called empirical formulas, which use letters and numbers indicating the numerical proportions of atoms of each type.

Isotopes

• Isotopes is when each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons. All isotopes of a given element have the same number of protons in each atoms.
• Isotopes have the same atomic number but different mass numbers.

Isotopes

• An isotope is a form of a chemical element where the atomic nucleus contains a specific number of neutrons, in addition to the number of protons that defines the element.
• The nuclei of most atoms contain neutrons as well as protons.

Isotopes

• Some examples of stable isotopes are isotopes of carbon, potassium, calcium and vanadium.

Isotopes

• There are two types of isotopes and they are radioactive isotopes and stable isotopes.
• Stable isotopes have a stable combination of protons and neutrons while Radioactive isotopes have an unstable combination of protons and neutrons, so they have unstable nuclei.

Periodic Table

• A periodic table is a table which contains all of the chemical elements arranged in order from the atomic number and they also in vertical columne.
• The alkaline earth metals are six chemical elements in column 2 of the Periodic table. They are beryllium, magnesium, calcium, strontium, barium, and radium.

Periodic Table

• The 38 elements in groups 3 through group 12 of the periodic table are called the "transition metals." The transition elements are both ductile and malleable, and they can produce electricity and heat.
• The alkaline earth elements are metallic elements found in the second group of the periodic table.

Periodic Table

• They are very reactive, electropositive, monovalent metals forming strongly alkaline hydroxides.
• The alkali metals, found in group 1 of the periodic table and they are very reactive metals that do not occur in nature.

Periodic Table

• Some examples of a noble gas are helium, neon, argon, krypton, xenon, and radon.
• hydrogen Metals are a solid, shiny, ductile, and a malleable object. They tend to take the shape of a solid object.

Metals vs Nonmetals vs Metalloids

• Nonmetals are brittle, not malleable or ductile, poor conductors of heat and electricity, and it tends to gain electrons in chemical reactions.
• It is a chemical element that mostly lacks metallic attributes. Physically, nonmetals tend to be highly volatile (easily vaporized), have low elasticity, and are good insulators of heat and electricity.

Metals vs Nonmetals vs Metalloids

• Chemically, they tend to have high ionization energy and electonegativity values, and gain or share electrons when they react with other elements or compounds. Seventeen elements are generally classified as nonmetals; most are gases (hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, and radon); one is a liquid (bromine), and a few are solids.

Metals vs Nonmetals vs Metalloids

• (carbon, phosphorus, sulfur, selenium, and iodine).
• Metals are a solid, shiny, ductile, and a malleable object. They tend to take the shape of a solid object. Most metals are solid at room temperature, but this does not have to be the case.
• Alloys are mixtures, where at least one part of the mixture is a metal.

Metals vs Nonmetals vs Metalloids

• Most metals are hard, shiny, they feel heavy and they melt only when they are heated at very high temperatures. Lumps of metal will make a bell-like sound when they are hit with something heavy (they are sonorous). Heat and electricity can easily pass through a metal (it is conductive). A lump of metal can be beaten into thin sheet (it is malleable) or can be pulled into thin wires.

Metals vs Nonmetals vs Metalloids

• Metalloids are somewhat between a cross of metals and nonmetals objects. Some example would be like water and any other types of liquids. Metalloids are the elements found along the stair-step line that distinguishes metals from non-metals. This line is drawn from between Boron and Aluminum to the border between Polonium and Astatine.

Metals vs Nonmetals vs Metalloids

• Metalloids have properties of both metals and non-metals. Some of the metalloids, such as silicon and germanium, are semiconductors. This means that they can carry an electrical charge under special conditions. This property makes mettalloids useful in computers and calculators.

Diatomics

• A diatomic molecule are made up of atoms from two different elements.
• The seven diatomic elements are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine.
• If a diatomic molecule consists of two atoms of the same element, such as hydrogen or oxygen, then it is said to be homonuclear.

Diatomics

• If a diatomic molecule consists of two different atoms, such as carbon monoxide or nitric oxide, the molecule is said to be hetero-nuclear. The noble gases (helium, neon, argon, krypton, xenon, and radon) are also gases at STP, but they are monotomic.

Diatomics

• The homonuclear diatomic gases and noble gases together are called "elemental gases" or "molecular gases", to distinguish them from other gases that are chemical compounds.
• At slightly elevated temperatures, the halogens bromine and iodine also form diatomic gases. All halogens have been observed as diatomic molecules, except for astatine, which is uncertain.

Diatomics

• Other elements form diatomic molecules when evaporated, but those diatomic species repolymerize when cooled. Heating elemental phosphorus gives diphosphorus. Sulfur vapor is mostly disulfur. Dilithium is known in gas phase. Ditungsten and dimolybdenum form with sextuple bonds in the gas phase. The bond in a homonuclear diatomic molecule is non-polar.

Ions & Ionic Compounds

• Ionic compounds are compounds that are made up of ions that charged particles that form when an atom gains or loses electrons.
• An atom can requires a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.

Ions & Ionic Compounds

• An Ion is an atom or a molecule with an electric charge due to the loss or gain of electrons.
• Its is also a charged atom or molecule. It is charged because the number of electrons do not equal the number of protons in the atom or molecule.

Ions & Ionic Compounds

• It is also of two or more forms of a chemical element, having the same number of protons in the nucleus, or the same atomic number.
• but having different numbers of neutrons in the nucleus, or different atomic weights. Isotopes of a single element have almost the same identical properties.

Ions & Ionic Compounds

• An ionic compound is a chemical compound that is held together by ionic bonding.
• An ion is an atom or group of atoms in which the number of electrons is different from the number of protons.

Ions & Ionic Compounds

• Ionic compounds have a high melting point and a boiling points. They are hard and brittle and as solids, they are almost always electrically protected, but when melted or dissolved they become highly conductive, because the ions are mobilized.