Week 4 - Chemical Sciences Part 1 Flashcards
What is matter?
Takes up space and has mass
What are the four elements
Earth
Fire
Air
Water
It was once believed that everything consisted of these 4 elements but now is classified by atomic properties seen on periodic table of elements
Atomic number
Atomic number goes up - number of protons
Atomic weight not shown - approximately double
What it as atom
Generic term which focuses on structure
What is an element
Properties and name
What is a compound
Different elements joined together
Atom has three particles- what are they and where are they situated
Protons - positively charged
Nutron - no charge
Electron - negativity charged
They are located in the nucleus of the atom
What happens to electrons?
Cannot change the nucleus of an atom so we focus on the electrons (spin around the outside)
Electrons spin in rings (Shells) and there are specific numbers in each shell
First - 2
Second - 8
Third - 8
The outer shell can beg, borrow, steal or give up electrons - these are called valence electrons
What is a compound?
A compound is a molecule that contains at least two different elements - all compounds are molecules but not all molecules are compounds.
What is a molecule?
Formed when two of more atoms join together chemically
Why do molecules/compounds stay together?
Valence electron is outer most electron shell associated with the atom and the different types of bonds between the electrons
Octet rule
Atoms lose or gain electrons until they are surrounded by 8 valence electrons
What is a covalent bond?
Bond formed between two or more atoms by a sharing of electrons (they can be polar or non polar)
Iconic bond?
Bond formed on the basis of electrostatic forces that exist between oppositely charged ions - ions are atoms by transfer of one or more electrons
When an atom loses an electron, it loses a negative charge and becomes a positive ion
When an Atom gains an electron, it gains a negative charge and becomes a negative ion
Metallic bond
Bonding in which the bonding electrons are relatively free to move throughout the 3D structure
Chemical bond
Force of attraction which holds two or more atoms together
That force of attraction is between one or more valence electron (negativity charged) held by one of the atoms at the positively charged nucleus of the second atom
What are polar and non polar covalent bonds
Polar - unequal sharing
Type of chemical bond where a pair of electrons are unequally shares between two atoms
Not shared because one atoms spends more time with the electron than the other atom
One has a stronger pull
Non polar - equally sharing
Two atoms share a pair of electrons with each other
Glue two atoms together to form a molecule
Requires a lot of energy to break this
Mass of atom?
Atoms mass comes from the weight of its nucleus
Atomic number refers to the amount of protons it has
Atomic mass = how many protons and how many electrons
What is volume?
The amount of space an object occupies
Measurement of space inside a 3D object
How is mass different from weight?
Mass is how much stuff is in an object
Weight is determined by gravity - how much pull to the earth
What is density?
Measure of how tightly packed matter is in the substance
Bigger nucleus, higher atomic number - more dense and a higher atomic weight
Alternative conceptions about matter?
Students think that something is large in size - heavier in weight
What is particle theory?
Matter is made of particles including atoms, molecules and compounds
Each substance has unique particles that are different from other substances
Particles of matter are held together by very strong forces
Temperature effects speed of particles - higher is faster, cool is softer
What are states of matter?
Solid, liquid and gasses
CDSU for Solids
Atoms/molecules move but in the same position relative to one another
They will vibrate and stay in the position they are in
Liquid CDSU
Molecules move around each other and change position relative to one another while staying in contact
They are always touching
Gas CDSU
Molecules spend most of their time alone
Zip through an empty space and hit one another
May only meet once and never again
Gas can expand more than solids and liquids because it is an empty space
Gas microscopic level
Assumes shape and volume of its container
Compressible - lots of free space between each molecule/compound
Flows easily - can move past each other
In this phase there are weak molecular forces
Liquid microscopic level
Assumes the shape of container it occupies
Can slide past each other
Not easily compressible - little free space
Flows easily
Molecular forces are weaker than in a solid
Solid microscopic level
Retains a fixed volume and shape - locked into place
Not easily compressible - little free space
Does not flow - cannot slide past each other
Molecules are closely bound by molecular forces
What does changing states require?
Requires energy - mainly in the form of heat
Is water vapour smoke?
No - this is an AC
Ask students what it looks and smells like
