Simple Ionic Compounds

Ionic Compounds with Multivalent Metals

Molecular Compounds

When all electrons are at their lowest possible energy level, the atom is said to be at ground state.

A valence electron can jump to a ELECTRONS higher energy level if it absorbs the right amount of energy (from heat, electricity or light). The amount of energy absorbed by the electron is a fixed amount. It must be enough to allow the electron to reach the next energy level, otherwise the electron will go nowhere. An electron that has jumped to a higher energy level is called excited and is very unstable. The atom is said to be in an excited state.

The electron does not stay excited for very long. It quickly falls back to its ground state energy level. As it falls down, it releases energy in the form of light (photon) The colour of light released is determined by the energy difference of the two levels.

1. All Matter is made up of particles 2.• The spaces between the particles are large compared to the particles themselves 3.• All particles of one substance are the same • Different substances are composed of different types of particles 4. • The particles are in constant Random motion Motion (Kinetic Energy) increases as the temperature increases 5. There are attractive forces between the particles. • Particles that are close together have stronger attractive forces than particles that are far apart.

Gas particles move in straight lines

• There are no attractive forces between gas particles because they are so far apart.

Gas particles move in straight lines

• When gas particles collide with a container or other particles, there is no loss of energy (perfectly elastic)

a temperature at which particles have no kinetic energy, no movement. According to calculations, this temperature is -273 C.

1) Democritus was a Greek philosopher (470-380 B.C.) who is the father of modern atomic thought. He proposed that matter could NOT be divided into smaller pieces forever. He claimed that matter was made of small, hard particles that he called “atomos” 2)John Dalton created the very first atomic theoryDaltonviewed atoms as tiny, solid balls. His atomictheory had 4 statements… Dalton’s Theory 1. Atoms are tiny, invisible particles. 2. Atoms of one element are all the same. 3. Atoms of different elements are different. 4. Compounds form by combining atoms. 3) J.J. Thomson discovered electrons.He also proposed the existence of a (+) particle…His atomic model was known as the “raisin bun model”… 4) Rutherford discovered protons and the nucleusHe called these (+) particles protons. He called the center of atoms the nucleus 5) Niels Bohr improved on Rutherford’s model.He proposed that electrons move around the nucleus in specific layers, or shells. 6) Chadwick discovered neutrons. He called these particles neutrons. Working with Rutherford, he discovered particles with no charge. Neutrons are also found in the nucleus. 7) The Modern Model (1932-) Work done since 1920 has changed the model. It is impossible to know where an electron is at any given time

matter is anything occupies space and has mass can be solid liquid or gas

SOLID

LIQUID

GAS

Protons + charge

Neutrons - charge

Electrons no charge

A characteristic that you can observe or measure without a chemical change

QUALITATIVE PROPERTIES Properties that are described by a description of sensory information. Examples: • Odour •Colour •Texture •Lustre

QUANTITATIVE PROPERTIES A property that is described by a measurement/ number and unit. Examples: • Density (for instance water has a density of 1 g/mL) • Boiling and Melting Points (for instance water boils at 100 C)

Physical Changes do NOT result in the formation of a new substance.

Chemical Changes result in the formation of a new substance.

Chemical Properties describe how a substance behaves in chemical reactions. Examples: 1.Combustibility 2.General Reactivity 3.Radioactivity 4.Corrosion 5.Reaction with Water 6.Reaction with Acid

A combination of the work of Bohr and Rutherford: n the Bohr-Rutherford model of the atom, each energy level or orbit has a certain amount of energy.  The closer to the nucleus an energy level is, the less energy electrons in that orbit have. Electrons in Energy Level 1 have the least energy. Electrons in energy levels that are further away have more energy.  Electrons CANNOT exist between energy levels

Each Energy Level can only hold up to a maximum number of electrons. The first energy level can only hold 2 electrons, the 2nd energy level can hold 8, and the 3rd can hold up to 18 electrons Electrons at lower energy levels are more stable than electrons at higher energy levels. Electrons at higher energy levels have more energy. Electrons in the outermost energy level of an atom are called the valence electrons

For atoms of a given element, the number of protons is ALWAYS the same

Atoms that differ only in the number of neutrons, but have the same number of protons, are called isotopes the different isotopes of an element has different masses

As well, atoms can gain or lose electrons to become charged particles called ions

Periodic Table of Elements – a table of the elements, arranged by atomic number, that shows the patterns in their properties; based on the periodic law

Dmitri Mendeleev  In the 1860’s he devised a periodic table where the elements were ordered by their atomic masses  He did this by grouping elements together according to their properties (density, reactivity, melting point, etc) it help predict new elements

Atomic size increases as you go down a column (group) because you are adding new orbits, making the atom bigger. Atomic size decreases as you go across a period (row)because there is a larger fraction of the (+) protons devoted to attracting the VALENCE electrons (-).

The reactivity of an element is related to how close it is to obtaining a FULL VALENCE (outermost) orbit. This means the trend is different for metals and for non-metals. Metals: The metal most likely to lose an electron to obtain a complete valence orbit is Francium. This is because it only has 1 valence electron that is held very loosely because its atom is so large. It is therefore the most reactive metal. Non- Metals: The non-metal most likely to gain an electron to obtain a complete valence orbit is Fluorine. This is because it only needs 1 valence electron, and since the atom is so small, it has the strongest pull from the positive nucleus. It is therefore the most reactive non-metal.

Atomic Number:  Is the number of protons in the nucleus of that atom Every element on the Periodic Table has an unique atomic number It is also equal to the number of electrons in a neutral (uncharged) atom

Mass Number:  Is the mass of the atom  It equals the total number of protons and neutrons together (you need to round the decimal number first)

Neutrons  To find the number of neutrons, do: # Neutrons = Rounded Mass Number – Atomic Number

Electrons  An atom’s overall charge is zero (they are neutral)  This means the positively charged protons must be equal to the negatively charged electrons p + e = 0 (for all atoms)  Also means, that the number of protons is the same as the number of electrons in a neutral atom

Metals

Non-Metals

Metalloids

bateries: provides energy to circuit

switch turn the circit on and off

fuse: stops flow when heated to high tempretures

light bulb : produces light

motor: produce wok energy

resistor: sloes doen the flow of electrons

Electric current is measured in amps (A) using an ammeter

Voltage is measured in volts (V) on a voltmeter Voltmeters are connected in parallel to either a load or battery.

wire: connects parts of the circuit

Current: flow of charge (electrons) within a conductor or how fast charge is moving. •Charge will only flow if there is a voltage source (potential difference). •Symbol for Current = I •Unit for Current = Amps (A) Electric current is measured in amps (A) using an ammeter

Electrical Potential is the amount of stored electrical potential energy in an electron in an instant in time that is based on its separation from positive charge

Voltage: The difference in electrical potential energy in two places in a circuit. As the electron does work on a load, it loses some of its electrical potential energy. The difference in electrical potential energy before and after a load (or across a battery) is the Potential Difference (also called voltage) •Symbol for voltage = V •Unit for voltage = Volts (V) Voltage is measured in volts (V) on a voltmeter Voltmeters are connected in parallel to either a load or battery.

• Resistance: opposes the push from the voltage source. Resistance affects the speed of the current. • Symbol for Resistance = R • Unit for Resistance = Ohms (Ώ)

Static electricity occurs when there is a build up of electric charge on the surface of a material. •It is called static electricity because the charges don’t move.

An excess or shortage of ELECTRONS produces an electric charge (remember protons don’t move) •Too few electrons for # or protons = positive charge •Too many electrons for # or protons = negative charge

1. Opposite Charges Attract 2. Like Charges Repel 3. A charged object attracts an electrically neutral object!

LIGHTNING RODS •A lightning rod is the highest point in the area. •When a lightning bolt strikes, it hits the lightning rod. •The electrons are carried around the building and into the ground by a heavy conductor, often made of braided copper wire.

An electrical insulator is a material in which charges cannot move easily.

An electrical conductor is a material in which electrons move easily.

When a charged object is brought close to a neutral object, the neutral object undergoes some form of “polarization” or “charge separation”, and the objects

Since electrons move in conductors, only conductors show true charge separation over an entire object. The electrons are free to move fully move away from the atoms they were originally associated with.

Since electrons are NOT free to move away from atoms/molecules in insulators, they can only shift to the one side of the atom or molecule they are associated with, so polarization in insulators is different than in conductors.

Charging by Friction Charge (electrons) can be transferred when two different, neutral substances are RUBBED together Works only when both substances are insulators,

CHARGING BY CONTACT NEUTRAL OBJECTS CAN BE CHARGED BY CONTACT WITH A CHARGED OBJECT.  If a positively charged object touches a neutral object,the object is postive tooIf a negatively charged object touches a neutral object,the object is negative too When the charged object touches the neutral object, electrons are disperse so that they are equally shared between the two objects In charging by contact, the neutral object being charged must be a conductor

Induction is the term given to the process that happens when acharged object is used to create: i. Charge Separation/polarization on another object (temporary induction) without touching it. CHARGE SEPARATION/POLARIZATION BY INDUCTION (TEMPORARY INDUCTION) • Bringing a charged rod near the electroscope will INDUCE the same charge on the foil leaves on the bottom • A negative rod forces electrons down and temporarily makes the foil leaves negative • A positive rod attracts electrons up and temporarily makes the foil leaves positive • Bringing a charged rod near the electroscope will INDUCE the same charge on the foil leaves on the bottom • A negative rod forces electrons down and temporarily makes the foil leaves negative • A positive rod attracts electrons up and temporarily makes the foil leaves positive

ii. Permanent charge on an object without touching it Both insulators and conductors can obtain charge separation by induction (i), but only conductors can be charged permanently by induction (ii PERMANENTLY BY INDUCTION •Requires grounding •Grounding a conductor means to connect it, through some conduction material to the ground (Earth).

Voltage in Volts: V = IR

Resistance in Ohm’s: R = V / I

Current in Amps: I = V / R

Series Circuit • An electrical hook-up in which current has only one path to follow. Series Circuit • Electrical loads SHARE the electrical pressure in a series circuit

Parallel Circuits • An electrical hook-up in which current has more than one path to follow. Electrons only have more than one path to follow Electrical loads do not share the electrical pressure

Ohm's Law: , as the potential difference increases, so does the current. as the potential difference increases, so does the current , as the potential difference increases, so does the current as resistance increases, current decreases as resistance decreases,current increases as resistance increases, potential difference also increases as resistance decreases,potential difference also decreases

Series Circuits: tI= I1=I2=I3 Vt= V1+V2+V3

Parallel Circuits: It= I1+I2 + I3 Vt = V1 = V2 = V3