Chemistry Exam Sem 1 Yr11

atom

all matter is made up of atoms, atoms are made up of smaller particles. The fundamental building blocks of chemistry

Nucleus

The central part of an atom

Protons

Positively charged particles found in the nucleus

Neutrons

Neutral particles found inside the nucleus

Electrons

Negatively charged particles that orbit the nucleus

In each atom the number of protons will always be the same number of \_______

electrons ( to ensure the overall charge is zero )

Element

a substance that is made up of just one type of atom. There are over 100 been discovered

Atomic number

this is the number of protons inside the nucleus of an atom

Mass number

this is the number of protons and neutrons in the nucleus of an atom

To calculate the number of neutrons

Mass number (top) - atomic number (bottom)

The Atomic number is ALWAYS the \_______ number next to the element. The mass number is always the \______ number.

smaller, bigger

How many electrons in shell 1

2

How many electrons in shell 2

8

How many electrons in shell 3

8

How many electrons in shell 4

Whatever is left

Ion

An atom with a charge

If an atom loses an electron it becomes

positively charged

If an atom gains an electron it becomes

negatively charged

Cation

A positively charged ion

Anion

A negatively charged ion

Metals lose electrons to become

positive ions (cations)

Non- Metals gain electrons to become

negative ions (Anions)

Who created the periodic table

Dmitri Mendeleev (Russian) based on the properties of Elements known in 1869

How many elements in the periodic table

118 (92 naturally occuring)

The periodic table is organised based on \______

atomic number (number of protons)

Atoms with the same atomic number have \__________

identical properties

Groups are the \_________

columns

Periods are the \__________

rows

Mass number \= \_________ + \__________

protons + neutrons in an atom

Group 1 on the periodic table

Alkali metals (very reactive with water)

Group 2 on the periodic table

Alkali Earth metals

Group 7 (aka 17) on the periodic table

Halogens (brightly coloured)

Group 8 (aka 18 or 0) on the periodic table

Noble Gases (very unreactive)

The block in the middle

Transition metals

Group 1 elements all have \___ electron in the outer shell

one

Group 2 elements have \___ in the outer shell

two

Group 7 elements have \______ in the outer shell

seven

Group 8 (aka group 18 or 0) have a \________ outer shell

complete

valance shell

The outermost shell

valence electrons

The electrons in the valence shell

Compound

two or more elements chemically bonded

Ionic bond

The two atoms are attracted to each other due to opposite charges

What do ionic compounds have in common?

•Made of positive and negative ions

•Usually solid at room temperature

•High melting points because ionic bonds are very strong

•Dissolve in water to form aqueous solutions. Aqueous solutions conduct electricity

Atoms can achieve a full outer shell of electrons by \________

sharing

Covalent bond

Non-metals share electrons to form covalent bonds

Electron Dot Diagrams

Diagrams to show how valence electrons and how they are shared

Covalent Compound Properties

•Exist as gas, liquids or solids with low melting points as covalent bonds are weak

•Generally don't conduct electricity because they aren't made of ions

•Usually don't dissolve in water

Metallic bonding

Occurs when a group of metal atoms shares a cloud of valence electrons

• sea of free floating valence electrons

• not attached to any one atom

• free to move

Metallic bonding properties

malleable, ductile, good conductor of heat and electrons

Mineral ores

When Earth formed, reactive metals (Al, Zn, Cu and Fe) reacted with other elements to form

Reactivity of metals

how easily metals give away their outer electron

metal + acid \=

salt + hydrogen gas

Properties of metals

• Luster = shiny

• Sonorous = ringing sound

• Ductile = stretched into wires

• Malleable = bent into shape

• conductivity = heat and electricity travel through easily

• High melting point = can be used in high temperatures

To name simple compounds of metals and non-metals:

1. Write down the name of the metal.

2. Write down the name of the non-metal, changing the ending of the word to "-ide".

Naming compounds containing oxygen

For compounds containing two elements plus oxygen, the ending of the other non-metal usually changes to "-ate".

e.g. nickel + sulfur + oxygen = nickel sulfate

Chemical bond

An attractive force that holds two atoms together. Chemical bonds are broken or formed during chemical reactions.

delocalised

Able to move freely from one place to another. The valence electrons in metals are delocalised so they can move freely between atoms.

electron configuration

The arrangement of electrons in shells around an atom's nucleus. Nitrogen has the configuration 2.5 while magnesium has the configuration 2.8.2.

electron shell

A grouping of electrons around the nucleus of an atom. Electron shells increase in energy level with distance from the nucleus.

lattice

A repeating arrangement of atoms in a solid. Lattices are highly ordered structures held together by bonds between atoms.

metal

A shiny, malleable element that conducts heat and electricity. Metals include magnesium and calcium. They tend to form cations by losing valence electrons.

molecule

A group of atoms bonded together. An oxygen gas molecule is made up of two oxygen atoms bonded together.

neutral atom

An atom with no net charge. An atom is neutral when it has an equal number of protons and electrons.

noble gas

An element that is non-reactive due to its full valence shell. The noble gases have full valence shells so they don't tend to form chemical bonds with other atoms.

non-metal

A dull, brittle element that does not conduct heat or electricity. Non-metals include sulfur and oxygen. They tend to form anions by gaining valence electrons.

periodic table

A grid arrangement of all known elements in order of atomic number. The modern periodic table was developed by Dmitri Mendeleev in the 1860s.

valence shell

The outermost occupied shell of an atom. Atoms form bonds to obtain full valence shells. They can do this by transferring or sharing electrons.

isotopes

Same element that has the same atomic number (same number of protons) but a different mass number (number of neutrons). E.g., Carbon 12 (12 \= mass number and 6 \= protons) Carbon 13 (13 \= mass number and 6 \= protons)

Metallic structure

Metallic bonds are strong, so metals can maintain a regular structure and usually have high melting and boiling points.

Ionic bond

The two atoms are attracted to each other due to opposite charges

What do ionic compounds have in common?

•Made of positive and negative ions

•Usually solid at room temperature

•High melting points because ionic bonds are very strong

•Dissolve in water to form aqueous solutions. Aqueous solutions conduct electricity

Covalent bond

Non-metals share electrons to form covalent bonds

Covalent Compound Properties

•Exist as gas, liquids or solids with low melting points as covalent bonds are weak

•Generally don't conduct electricity because they aren't made of ions

•Usually don't dissolve in water

Metallic bonding

Occurs when a group of metal atoms shares a cloud of valence electrons sea of free floating valence electrons not attached to any one atom are free to move

Metallic bonding properties

malleable, ductile, good conductor of heat and electrons

element

Elements are pure substances that are composed of only one type of atom. There are over 100 discovered

compound

Compounds are substances that are formed by two or more different types of elements that are chemically bonded

To name simple compounds of metals and non-metals:

Write down the name of the metal.Write down the name of the non-metal, changing the ending of the word to "-ide".

What is the name of the compound made when the following elements combine? magnesium and oxygensodium and chlorineoxygen and iron

magnesium oxidesodium chlorideiron oxide

Naming compounds containing oxygen

For compounds containing two elements plus oxygen, the ending of the other non-metal usually changes to "-ate".

e.g. nickel + sulfur + oxygen = nickel sulfate

ion

An atom with a charge

If an atom loses an electron, it becomes positively charged. If an atom gains an electron, it becomes negatively charged.

Cation: positive charge

Anion: negative charge

collision theory

Particles must collide with enough energy and correct orientation in order to react

unsuccessful collision

reactant particles approach each otherthey collide with the incorrect orientationreactant particles separate

successful collision

reactant particles approach each otherthey collide with the correct orientationproducts formed

How to speed up reaction rates

concentration, temperature, surface area, catalysts/enzymes

concentration

more reactants will allow for more collisions

temperature

higher temp means particles collide more as they move more

surface area

more places for successful collisions

Catalysts/enzymes

proteins that help making/ breaking bonds therefore speeding up reactions. (without enzymes life wouldn't exist)

Biological Catalysts are proteins that:

• Lower the activation energy

• Speed up rate of reaction

• Don't get used up in the reaction

e.g. Amylase breaks down carbohydrates into glucose

rate of reaction

How quickly the reactants react to form the product

rate of reaction (formula)

amount of reactant used or product formed / time

when do reactions occur

Reactions happen when particles (the reactants) collide with enough energy to become chemically joined

Precipitation Reactions

When two solutions containing soluble salts produce an insoluble solid called a "precipitate".

precipitate

A solid that forms from a solution during a chemical reaction.

Precipitation

a reaction between two solutions that forms an insoluble solid

Corrosion

Wearing away of a metal (Rust) Air, water and chemicals in air and water can be corrosive (eg. salt water)

Combustion

When a substance reacts with oxygen to form carbon dioxide and water. A compound containing carbon and hydrogen (and sometimes oxygen) combines with oxygen gas to produce carbon dioxide and water. e.g. hydrocarbon + oxygen -\> carbon dioxide + water + heat and light CxHy(Oz) + O -\> CO2 +H2O

oxidation-reduction/redox reaction

reaction that involves the transfer of electrons between atoms

Common redox reactions:

•Combustion

•Respiration

•Corrosion

•Photosynthesis