1.0 1.0 Scientific Method

Steps

• Observe

• Identify

• Research

• Hypothesis

• Test

• Observe and Analyze

• Draw conclusion

• Report

  Variables- things that change during an experiment

• Independent Variable- That you can control

• Dependent Variable- that changes as the independent variable change.

• Controlled Variable-never change

Trials- is one run experiment, at least 3 times.

Research Skills

1. Initiating and planning-

   Hypothesis -a possible ans. or educated guess

   Prediction- a statement that predicts the outcome of a controlled experiment Experimental Design- Brief description of the procedure by which a hypothesis is tested.

2. Performing & recording- Qualitative(not measured by #.

   Quantitative Observation- measured by numbers.

3. Analyzing & Evaluating- Graphs can be used to show patterns.

4. Communicating- Share you results

5.1

Matter- anything that has a mass and takes up space (volume)

The Particle Theory of Matter-theory that describes the behavior and composition of matter

• All matter is made up of tiny particles that have empty spaces between them

• Different substances=different kinds of particles.

• All particles are in constant random motion

• The particles of the substances move faster as its temperature rises.

• Particles attract each other

  Classification of matter

  • Pure substances- made up of only one type of particles. Exp, Gold & Water

    A) Elements- Pure substances that cannot be broken down into simpler substance.

    *Made up only one type of atom. Exp, Aluminum

    B) Compounds- Compounds that are made up of molecules, contain 2 or more different elements in a fixed proportion. Exp, Water (H2O) or (H-O-H)

Mixtures- A substance that is made up at least 2 different types of particles.

A) Mechanical Mixtures- A mixture that you can see the difference. Exp, granola bar.

B) Solutions- A uniform mixture of 2 or more substances. Exp, juice.

5.2

Physical Properties- determined by observing a substance using 5 senses.

Qualitative- not measured by #.

Quantitative Observation- measured by numbers.

Other Physical Property

Luster- Shininess or Dullness

Optical Clarity- The ability to allow light through (transparent, translucent, opaque)

Brittleness- Break-ability or flexibility

Viscosity- the ability of a substance to flow or pour readily.

Hardness- The relative ability to scratch or be scratched by another substance.

Malleability- the ability of a substance to be hammered into thin sheets (exp. Aluminum)

Ductility- the ability of a substance to be pulled into a thin strand (exp.copper)

Electrical Conductivity- the ability of a substance to allow an electric current to pass through it.

Physical Changes- the ability of the substance remains exactly the same. ( exp. Ice turn to water)

Clues of Physical Change

1. Change in Shape or Form but NO NEW SUBSTANCE IS PRODUCED.

2. Change of State

3. Solubility (Dissolving)

4. MOST PHYSICAL CHANGES ARE EASY TO REVERSE.

5.3

Chemical Properties- A change is the difference from its starting substance to it’s final substance.

Chemical Changes- A change in the starting substance or substances to the production of one or more new substances.

- The original substances do not appear.

-Instead the components are rearranged.

5 CLUES OF CHEMICAL CHANGE

1. Chnage in color

2. Change in odor

3. A gas or bubbles form without heat.

4. A new solid is seen.

5. A change in temperature or light.

5.6

Characteristic of physical properties

1. Density= Mass(g)/volume (mL & cm³)

2. Melting Point

3. Boiling Point

G=Given

R=Required

A=Analysis

S=Solve

Unusual Properties of Water

• high boiling and freezing points,

• high heat capacity

• being less dense as a solid (ice) than as a liquid,

• Solid form floats on it liquid form ( ice floats on water)

6.1

Element Symbol- a short form for a chemical element.

Metals-elements that are located on the left and central parts of the periodic table.

Non-metals-elements that are not metallic.

Metalloids- Have properties of both metals and non-metals and found in the staircase region.

Hydrogen- is a gas but found on the left side.

6.4

Chemical Families- a column of elements with similar properties on the periodic table.

Alkali Metals- Elements within the first column from the left side of the periodic table. (Group 1) highly reactive, shiny and silvery, soluble in water and form compounds that are white solids. (table salt & baking soda)

Alkaline Earth Metals- Elements within the second column. (Group 2) They are: shiny and silvery metals, and they form compounds that are insoluble in water. they are used in fireworks making a colorful flame especially Mg ( magnesium)

Noble Gases- Elements in the column on the far right of the periodic table. (Group 18 ) These gases do not form compounds, they do not react chemically and they are stable (inert) These gases glow brightly when electrical current is passed through them.

Halogen- Elements that are to the left of noble gases. (group 17)Halogens are very reactive, and due to their reactive nature they often form compounds with alkali metals, and are rarely found in elemental form.

Period- a row on the periodic table

Trends- Elements in the same horizontal row (a period), show trends of increasing and decreasing reactivity. ***The reactivity of metals decreases from left to right, and decreases from bottom to top.

What Mendeleev did

-gathered information about properties of all known elements

-used masses of elements and put them in order by increasing mass

-he noticed that there were groups of elements that had similar physical and chemical properties and rearranged elements with similar properties under each other in the same column

-from this it led to rows with different lengths and led to the irregular shape of the periodic table 

-there were empty spaces since elements were not yet discovered

6.6

Important Contributions of Key Scientists in Atomic Theory

1. Democritus: Proposed that everything is made of tiny, indivisible particles called atoms. He was one of the first to suggest that these atoms were the basic building blocks of matter.

2. John Dalton: Developed the first atomic theory, suggesting that all matter is made of atoms, which are indivisible and indestructible. He proposed that atoms of the same element are identical in mass and properties, and compounds are formed by combining atoms of different elements.

3. J.J. Thomson: Discovered the electron in 1897 using cathode ray experiments. He proposed the "plum pudding" model, suggesting that atoms contain electrons embedded within a positively charged sphere.

4. Ernest Rutherford: Conducted the Gold Foil Experiment in 1909, which led to the discovery of the atomic nucleus. He proposed that an atom is mostly empty space, with a dense, positively charged nucleus at its center.

5. James Chadwick: Discovered the neutron in 1932, providing further evidence of the structure of the atomic nucleus, and contributed to the understanding of isotopes.

6. Niels Bohr: Proposed the Bohr model of the atom in 1913, introducing the idea that electrons orbit the nucleus in fixed paths (quantized orbits) and that the energy level of these orbits can vary.

Proton, Electron, and Neutron (PEN)

6.7

Atomic Number 🡪The number of protons in an atom’s nucleus

Mass Number- According to the atomic model, the atom is mostly empty space
Isotopes 🡪 An atom with the same number of protons but a different number of neutrons. E.g. Few naturally occurring lithium atoms contain only 3 neutrons

Atomic Mass- Found underneath the element symbol on the periodic table.

Patterns in the periodic table-Down the family: # of electron orbits increases

Within each family, all atoms have the same number of outermost (VALENCE) electrons

7.1

Chemical Formula- is used to indicate the type and number of atoms in a pure substance. Eg, water (H2O- H-O-H 3 in total)

Ca (NO3)2

3 × 2=6

Ca=1

N=1 × 2=2

O=3 × 2=6

Add the answers 1 + 2 + 6=9 atoms

A) Molecular Compound- a molecular that consists of 2 or more different non-metals. Eg, H2O and CO2

B) Ionic Compounds-between a metal and non-metals. These compounds are made up of changed particles called ION.

ION-when an atom loses or gains an electron.

7.2

Stability

• Atoms combine to become more stable

• stable means achieving a full valance shell (full 8 outer shell)

• Ionic Bond- Atoms may combine with other atoms to become more stable by losing electrons (metal and non-metal)

• Co-valance Bond Sharing electrons (between non-metal and non-metal)