Phys/Chem properties and changes
Two examples of Physical properties
Color
smell
mass
temp
Boiling point or Melting point
Smallest part of an Element
Atom
What subatomic particles make up an atom's nucleus
Protons and Neutrons
An atom becomes an ion when it gains or loses _______
Electrons
Identify the reactants in this chemical reaction: Zinc + Hydrochloric acid --> Zinc chloride + Hydrogen gas
Zinc and Hydrochloric acid
Phase change is a physical change. Explain why
Because Nothing New is Formed!
Smallest part of a compound
Molecule
What is atomic number?
The identity of an atom which is the number of protons ( also the number of electrons)
Protons are Positive particles and Electrons are Negative particles . An Atom is Neutral when they have an equal number of Protons and Electrons.
Giving or Taking electrons which happens between metals and non-metals is called ________ bond
Ionic
What is true about the equation :
H2O2 -----> H2 + O2
It represents a chemical reaction
Dissolving a physical change. Prove it.
For example, dissolve sugar in water, if you evaporate the water, crystals of sugar will be left behind. Nothing new is Formed, so it is a physical change.
Difference between Mixture and Compound
In a compound the substances that make it are bonded together but in a Mixture the substances are not bonded together
What is atomic mass (a.k.a atomic weight) ?
Protons + Neutrons
Sharing of valence electrons to get a full valence shell is called __________ bonding
Covalent
What does the subscript 2 in Na₂SO₄ mean?
There are 2 atoms of Na bonded into Na2SO4
What is Chemical change? What are some signs of chemical change?
Chemical change is when substances react and something new is produced . Signs of Chemical change:
color change, smell change, fizzing/bubbling, light produced, heat given off or taken in.
Kumar adds salt to water till the salt disappears. Is this a Mixture ? If so, what type of mixture (choose a/b):
a. Homogeneous
b.Heterogeneous
Yes
a. Homogeneous
How many electrons does Oxygen have ? How do you know
Oxygen has 8 electrons
Atomic number of Oxygen = 8
Atomic number = Number of protons (and also the Number of electrons)
Draw Bohr Model for Sodium (Na)
On the white board
Matter is neither created nor destroyed. In a chemical reaction you always end up with the same amount of stuff as you started with. What is this law?
Law Of Conservation of Mass
When baking soda and vinegar combine they fizz and bubble. This is a sign of chemical change. Explain why.
The fizzing and bubbling when baking soda and vinegar combine show that a gas is produced. Any time a new substance is produced , it is a chemical change.
Why are elements and compounds called pure substances
They are made up of only one type of particle
Outermost electrons for an atom is called the _______ electrons.
How do they relate to reactivity?
Valence electrons
Atoms want full valence shell, if they don't have full valence shell they react to get a full valence shell.
Draw Lewis Dot model for Aluminum (Al)
Draw on the white board
Chemical Formula for Propane
Teacher will draw the molecule on the whiteboard and the students have to identify the chemical formula