Chemistry

Properties of Ion Elements

When an atom gains or loses electrons becomes charged - ion. Electrons with a full valence shell have a charge of 0. Valence electrons means amount in outer shell

Metalloids

Zigzag arrangement, have properties similar to metals & non metals

How do electrons produce energy?

o Electrons absorb energy, jump into a higher orbital (excited) o As they come back down to ground state, release energy in the form of a photo, or light (colour) o Because unstable, it falls back down to its original level

Group 17 - Halogens ~ 1 -

17 electrons in valence shell. Form salts when they react with a metal. When halogens burn they become dangerous and toxic. Exist in a variety of states at room temp: Gas ~ fluorine and chlorine, Liquid ~Bromine, Solid ~ Iodine and astatine. Exist as diatomic molecules in their gaseous state - stable. Halogens are most reactive non-metals

What is an alpha particle?

2 protons & 2 neutrons - positively charged, no electrons 2+ charge. Very weak form of radiation (low energy), little penetrating power. Radium and uranium emits alpha radiation. Least dangerous. Helium nuclei. Can be stopped by a sheet of paper, cant go through skin

What is an anion?

A negatively charged ion

What is a net electric charge?

A normal element has no net electric charge because the protons balance out the electrons. By gaining electrons it becomes negatively charged and by loosing electrons it becomes positively charged.

What is a cation?

A positively charged ion

How are elements organised on the periodic table?

According to physical & chemical properties. Periods are horizontal, groups are vertical.

What is nuclear Fallout?

After a nuclear device has been detonated, radioactive nuclei & tonnes of irradiated dust are blasted into the atmosphere. Returns to the ground

What are the Chemical properties of Noble Gases?

All are gases at room temperature. Monatomic gases - atoms are not bound together. Get denser and heavier as you move down the group

What is an ion?

Atom or molecule with a net electric charge due to loss/gain electrons. Any atom with a net charge is an ion.

What is electron configuration?

Atoms try to achieve lowest energy level possible - most stable. How electrons are arranged in the electron cloud

What is ionic bonding?

Chemical bond that generates two oppositely charged ions. The metal loses electrons to become a positively charged cation. Nonmetal accepts those electrons to become a negatively charged anion. Since they've got opposite charged ions they're strongly attracted to each other - this is called ionic bonding.

What is an isotope?

Different number of neutrons - changes atomic mass. Same atomic number. Extra neutrons - hard for nuclear force to keep atom together (decays). Unstable nucleus breaks up, energy in form of radiation is release

Ernest Rutherford

Discovered atoms have small charged nucleus surrounded by largely empty space, and are circled by tiny electrons. Hypothesised neutron. Gold foil experiment.

JJ Thomson

Discovered the electron. Used a cathode ray tube to discover the electron. Plum pudding theory

Radioactive Isotopes in medicine benefits

E.g. Cobalt 60 - used in radiotherapy for treating cancer. Produces Beta Particles and Gamma rays. Targeted precisely- minimised damage to healthy tissue. Treats cancer and sterilises medical equipment, kills bacteria & pathogens, painless.

Radioactive isotopes in industry benefits

E.g. Uranium 235 - Nuclear power stations. Produces alpha and gamma radiation. When uranium-235 splits, incredible energy is produced as heat and gamma radiation. Effective at creating nuclear energy. No green house gasses - very efficient and produces a lot of energy.

Flame test

Easiest way of identifying the metal. Flame colours are produced from the movement of electrons in the metal ions (metal ions are present in compounds). The excitement due to heat caused them to move around orbital shells causing flames to change colour. Elements produce different colours because they have a different number of shells and electrons & different distances between shells.

Group 2 - Alkaline Earth Metals - 2+

Elements - Be, Mg, Ca, Sr, Ba, Ra. Have a low melting point, soft, metals react with water, increase in reactivity, increasingly soluble with a decrease in temperature. Shiny, readily lose 2 outermost electrons to form cations with 2+ charge.

What is the ocelot rule?

Elements lose, gain, and share electrons to form the required octet in their highest remaining energy level

What is first ionisation energy?

Energy needed to remove 1st electron

Radioactive isotopes in industry negatives

Expensive to buy nuclear reactors, accidents can release deadly radiation into the atmosphere. Produces a lot of waste, which is highly radioactive. Bombs

How many electrons can be held in each shell?

First shell - up to 2 electrons Second shell - up to 8 electrons Third shell - first 20 elements holds 8 electrons, after this it can hold up to 18

What is a Beta particle?

Form of radiation emitted by an atom. Consists of an electron (negatively charged) or a positron (-1). Very small mass and travels at very high speeds. Fired out when there are too many neutrons. Strontium and cobalt emit beta radiation. Stopped by Aluminium

What is used to measure radiation levels?

Geiger counter

Group 1 - Alkali Metals - 1+

Have 1electron in their orbital shell. Include Potassium, rubidium, sodium, lithium, caesium, francium. Most reactive of all the metals. Release of energy: fizzing, bubbling, heat, explosion. Must be stored in oil or sealed glass to prevent air getting to them As you go down the group: o More violent reactions with water and oxygen o Atomic radius increases o First ionisation energy decrease o Electronegativity decreases o Melting and boiling points fall

Group 18 - Noble Gases

Have 8 electrons in their outer orbital. Extremely rare in nature. Helium, neon, argon, krypton, xenon and radon. Noble gases are the most unreactive elements

James Chadwick

He discovered the neutron. The weight of the nucleus in atom was too great to only hold protons & there was only a positive charge coming from the nucleus meaning there was another particle with no charge in the atom. Used scattering data

What is Gamma Radiation?

High energy so high penetrating power, most damaging. Cobalt and americium is an example of Gamma radiation. Gamma rays have no mass and travel at the speed of light. Fired out when an atom is unstable due to too much energy. Stopped by lead. Has a charge and mass of 0.

What is electronegativity?

How strongly elements can attract electrons. Ability to attract electrons in a bond.

Radioactive isotopes in medicine negatives

Internal exposure can result in cancer, external exposure to radiation can result in burns, radiation sickness or death, radioactive weapon. Certain types can lead to damage to other body cells and infertility. Often suffer from tiredness, hair loss and skin conditions

Metals

Left side of periodic table, good conductors of electricity & heat, malleable, ductile, loses one or more electrons to create a positively charged ion. Have luster, tend to loose electrons.

What are diatomic molecules?

Molecules composed of two atoms of the same or different elements

What is nuclear fission?

Nuclei of large atoms split to form the nuclei of smaller atoms releasing energy in the form of radiation and heat

How does an element become radioactive?

Occurs when nuclei of atoms break up into the nuclei of other atoms. Split occurs - nuclei are unstable because have a high mass number or an imbalance of protons and neutrons. When it releases neutrons or protons it becomes radioactive. Radiation is released & a more stable nucleus is formed. When it looses neutrons it can stop being radioactive

What is nuclear radiation?

Protons in a nucleus stay together because of powerful nuclear force. When nucleus becomes very large, nuclear force may not be strong enough to hold nucleus & bits break off till it gets smaller & more stable. Nuclear radiation is the energy and particles released from a nucleus.

What is radioactive decay?

Radioactive isotopes decay over time. Each has a specific half life. Half life = time it takes for half of the atoms to decay

Nuclear Energy Technology

Radiotherapy, smoke alarms, carbon dating, x-rays, irradiation. Nuclear power station, nuclear weapons, chemical tracers to help with diagnosis.

Group 3 to 12 - Transition Metals

Relatively hard metals, high melting points. Many form coloured components with a non-metal e.g. chlorine. Metal has to bond w/ non metal to form a reaction - sharing electrons - H2O - 2 Hydrogen and 1 oxygen (2 goes with left letter)

Non-metals

Right side, poor conductors of electricity & heat, accepts electrons to form a complete outer shell (8 electrons). Dull, brittle, tend to gain electrons

Niels Bohr

Rutherford incorrect - shows atoms should be unstable & matter would fall apart. Atoms give of electromagnetic radiation which led to electrons jumping to different orbit levels and that electrons travel in separate orbits. Atom are small positively charged nucleus surrounded by orbiting electrons.

What is Vitrification?

Storing the nuclear waste created in nuclear reactors by mixing liquid waste with molten glass and pouring it into steel drums.

What is a radioisotope?

Term for a radioactive substance - a radioactive atom

John Dalton

Theory: elements are made up of extremely small particles called atoms & atoms of different elements are different in size and mass. Technology/Method: Classical analactical chemistry techniques including separations such as precipitation, extraction and distillation

What is food irradiation?

Treatment of foods with gamma rays, Xrays, or high-voltage electrons to kill potentially harmful pathogens and increase shelf life.

What is Nuclear fusion ?

Two small nuclei combine to form larger nuclei

What are Fission bombs?

Uncontrolled chain reaction - occur when a certain amount of radioactive material is present, critical mass

What are the chemical properties of Halogens?

Very reactive - Fluorine most reactive element on the periodic table, Reactive because have 7 valence electrons. One electron short of having a complete outer shell As you go down the group: o Melting and boiling points increase o Gets bigger & less reactive