Science

Elements, Compounds and Mixtures

All elements are listed in the periodic table

HOW TO DETERMINE IF SOMETHING IS AN ELEMENT OR NOT?

1.      It is a pure substance which means it is only make of one type of particle.

2.      It cannot be separated into simpler substances by chemical or physical means

3.      Each has a unique set of properties, it is also called characteristic properties can can be physical or chemical

4.      It is classified by their properties like METALS, NONMETALS and METALLOIDS>.

METALS
-shiny
-Good conductors
-Malleable
-Ductile
-Ex. Gold, silver and copper

NONMETALS
-dull, no shine
-bad conductors
-at room temp, only a few solids that are brittle
-Most are gases
-Ex. Hydrogen, Oxygen and helium

METALLOIDS
-Characteristics of metals and nonmetals
-Semi conductors
-Ex. Silicon and germanium

COMPOUNDS
-Found in nature more often than pure elements
-Have more than one element
-Elements are chemically bonded to eachother
-Pure substances that occur in fixed ratios by mass
-Cant be separated by physical means
-Have their own unique set of properties.

MIXTURES
-2 or more substances that are not chemically bonded, so diff. parts keep their own properties
-parts do not occur in definite ratio. Ex. 2 pepperoni pizzas
-Ex. Pizza, granite, Kool-aid, brass and Jello

HOW TO SEPARATE MIXTURES
1. Distillation
2. Magnet
3. Centrifuge
4. Filtration
5. Evaporation

MORE ABOUT MIXTURES
-Can be heterogeneous or homogeneous
- Homogeneous mixtures are called solutions
- Heterogeneous mixtures are called suspensions
- Colloids are calssified as heterogeneous in some books and homogeneous in others.

LESSON 2 – STATES OF MATTER

MATTER
-defined as anything that possesses mass and occupies space. Everything in our surroundings is composed of matter, including air,  water, rocks and even ourselves.
-Matter can exist in various states, each exhibiting unique properties.

SOLIDS
-particles are tightly packed and held together by strong forces
-Shape: fixed shape and volume
-particle movement: particles vibrate in place but don’t move freely

LIQUIDS
-particles are close together but no as tightly packed as in solids, allowing them to flow.
-Shape: take the shape of their container but have a fixed volume (no fixed shape)
-Particle movement: particles slide past eachother

GASES
-expand to fill the shape and volume of their container
-particle arrangement: particles are far apart with lots of space between them
-Movement of particles: particles move quickly and freely in all directions

PLASMA
-Consists of electrically charged gas, where particles are ionized and carry a charge.
-resembles a gas but contains free electrons that can conduct electricity.
-Ex. Starts, lightning and neon signs

BOSE-EINSTEIN CONDENSATE (BEC)
-occurs at temperatures approaching absolute zero, causing particles to function as a single entity.
-Particles overlap and act like a “super-atom”
-BECs are solely created in laboratories and are not found in nature.
-Made by Albert Einstein and Satyendra Nath bose

KINECTIC THEORY OF MATTER
This understanding of particle motion helps to explain various phenomena in everyday life. for example, when a solid is heated, its particles gain energy and vibrate more vigorously, which can lead to the solid expanding. In liquids, increased temperature allows particles to move more freely, which can result in faster diffusion or evaporation. In gases, the high speed movement of particles mean they exert pressure on the walls of their container, a principle that is fundamental to understand has laws.

CHANGING STATES OF MATTER
Melting: Solid to liquid.  Example: Ice melting to water
Freezing: Liquid to solid. Example: water freezing to ice
Evaporation: Liquid to gas. Example: Water boiling to steam
Condensation: Gas to liquid  Example: Steam cooling into water droplets
Sublimation: Solid to gas without becoming liquid. Example: Dry ice.

LESSON 3 – PHYSICAL AND CHEMICAL CHANGES

WHAT HAPPENDS WHEN MATTER UNDERGOES CHANGES
-It can either stay the same (Physical change)
-It can either turn into something new (Chemical change)

PHYSICAL CHANGE
-affect the appearance or state of a substance but don’t change what the substance is.
-changes are often reversible
-no new substance is formed
-changes in size, shape or state
-Energy changes are small (like heat to melt or freeze)

INTENSIVE PROPERTIES
-Do not depend on the amount of matter in a sample
-Remain the same regardless of the size of the sample
-Ex. Temperature and boiling point: water boils at 100C wether it’s a liter or a cup

EXENTSIVE PROPERTIES
-Depends on the amount of matter in a sample
-change owhen the quantity of matter changes
-Ex. Mass, the more matter, more mass you have. Volume, a larger quantity of a substance occupies more space.

CHEMICAL CHANGES
-happens when a substance turns into something new
-Ex. Burning wood, creates ash and smoke
-Mixing vinegar and baking soda which produces carbon dioxide gas. Baking a cake
-new substances are formed
-Can produce gas, heat,light, or a solid
-Usually irreversible
-large energy changes occur

CHEMICAL PROPERTY
-describes the ability of a substance to change into a different substance.
CHEMICAL CHANGE
-the process by which a substance changes into a new substance

PHASE CHANGES
- are physical processes where a substance transitions from one state of matter to another, drives by temp., pressure or energy changes.

Melting (Solid → Liquid)

Occurs when a solid absorbs enough heat to overcome the forces holding its particles in a fixed structure.

•      Example: Ice melting into water on a hot day.

•      Heat energy causes the ice particles to vibrate more vigorously until they break free and flow as liquid water.

Freezing (Liquid → Solid)

Occurs when a liquid loses heat, causing its particles to slow down and form a fixed structure.

•      Example: Water freezing into ice in a freezer.

•      As the temperature drops below 0°C

Boiling (Liquid → Gas)

Happens when a liquid is heated to its boiling point, and particles throughout the liquid gain enough energy to form gas.

•      Example: Water boiling in a pot to make pasta

Evaporation (Liquid → Gas)

A slower surface-level transition where molecules with enough energy escape from the liquid phase into the gas phase, even below the boiling point.

•      Example: Clothes drying on a line.

Condensation (Gas → Liquid)

Occurs when gas particles lose energy and transition into the liquid phase.

•      Example: Water droplets forming on the outside of a cold glass

Sublimation (Solid → Gas)

A direct transition from solid to gas without passing through the liquid phase.

•      Example: Dry ice (solid carbon dioxide) sublimating into gas

Deposition (Gas → Solid)

A direct transition from gas to solid without passing through the liquid phase.

•      Example: Frost forming on a car window

LESSON 4 – PERIODIC TABLE OF ELEMENTS

After a series of revisions the early periodic table has evolved into its current version, by looking at the modern periodic table, we can see that the elements are arranged horizontally in order of increasing atomic number

ELEMENT
-each of thme is identified by its symbol placed at the middle of the square, the atomic number and the atomic mass are also indicated

GROUPS OR FAMILIES
-these the vertical columns.
-the elements in each column have similar chemical properties

GROUP A
Group 1A- Alkali Metal
Group 2A- Alkaline Earth Metals
Group 3A- Aluminum Group/Boron Family
Group 4A- Carbon Family
Group 5A- Nitrogen Family
Group 6A- Oxygen Family or Chalcogens
Group 7A- Halogens
Group 8A- Noble/Inert Gases

GROUP B
Transition elements are found between group 2A and Group 3A, while the inner transition elements (Lanthenides and actinides) are found at the bottom of the table

PERIODS
Consists of several horizontal rows called periods or series, there are seven periods which are designated as 1,2,3,4,5,6, and 7

Period 1- has 2 Elements
Period 2 and 3- each has 8 elements
Period 4 and 5- each has 18 elements
Period 6- has 32 elements
Period 7- has 14 elements

BLOCKS
Elements belonging to the same group have similar last sublevel configuration. Thus, using the electron configuration of the elements, the periodic table can be divided into 4 regions or blocks (s, p, d and f)

ELECTRON CONFIGURATION
-provides insight into the chemical behavior of elements by helping us to determine the valence electrons of an atom

METALS
Metals are elements having the highest degree of metallic behavior.

NONMETALS
These are elements showing less or no metallic properties than those of metals and metalloids.

METALLOIDS
All the elements having low degree of metallic behavior. It show some  metallic properties and some nonmetal properties.

LESSON 5 – HISTORY OF ATOMIC STRUCTURE

It took more than 2000 years before the ancient idea about the atom became a theory. Scientists have used early ideas as their guide for their own studies

JOHN DALTON 1766 – 1844
-proposed his theory of matter in 1803.
-He pictured the atom as a solid, indestructible sphere with a mass that is like a billiard ball.
-Dalton was an English chemist, physicist and meteorologist who conducted ground-breaking research into color blindness

JJ THOMSON 1856 – 1940
-After a series of investigations, he discovered that Dalton’s atomic model was not accurate.
- He was able to discover negatively charged particles known as electrons using a cathode ray tube.
- He was British physicist and a nobel prize recipient.
-he discovered the first electron

ERNESTO RUTHERFORD 1871 – 1937
-due to the discovery of the nucleus, His work was known as the nuclear model of an atom
- he was awarded the nobel prize in 1908 for his theory of atomic structure

NEILS BOHR 1885 – 1962
-After reviewing Rutherfords theory, he adapted plancks theory to rutherfords model of the atom.
-The Rutherford model had orbiting electrons moving around the massive nucleus of the atom.

ARNOLD SOMMERFELD 1868 – 1951
-Sommerfeld and Bohr expanded their studies to enhance bohr’s model of an atom.

BOHR – SOMMERFELD ATOMIC MODEL
-Summerfeld pointed out three refinements in Bohr’s Atom
1. The introduction of elliptical orbits
2. Allowance for an orbiting motion of the electrons
3. The consideration of relativistic mass effects.

SUBATOMIC PARTICLES
-Protons
-Neutrons
-Electrons

PROTONS
-has an electric charge of positive one and it is said to be stable by itself.
-It is a fairly heavy particle and resides in the dense nucleus of an atom

NEUTRONS
-has no net electric charge.
-Both proton and neutrons make up the nucleus of an atom.
- almost all of the mass in an atom comprised the protons and neutrons in the nucleus.

ELECTRONS
-It has an electric charge of -1
-Electrons are much smaller than neutrons and protons.
-They revolve somewhere outside the nucleus, since its mass is 1/1837 the mass of the proton.

“An atom is whole, but its various components and sub-systems are dependent on each other for existence and function. An atom cannot exist without its components; likewise, a component cannot exist without the others.”

“If electrons are removed from or added to a neutral atom, the same element will become a charged particle, and then ion will be formed.”

CATION
-The Ion with the positive charge
-formed when the electron is removed from an atom

ANION
-The Ion with the negative charge
-formed when an electron is added to an atom.

“Each element has a distinctive number of protons. This unique atomic number serves as the numeric identity of the element.”

“The sum of the numbers of protons and neutrons in an atom gives the mass of the atom or its mass number.”

ISOTOPES
-These are atoms of the same element that have the same atomic number but have different atomic mass.

Proton = Electron = Atomic Number

Mass number = Protons + Neutrons

Neutron = Mass number -Atomic number