Science Flashcards
What are mixtures? Explain the 2 types
A mixture is a combination of two or more substances that are physically blended but not chemically bonded. The substances in a mixture retain their individual properties and can usually be separated by physical means, like filtration or evaporation. Examples: saltwater, air, or a fruit salad.
Homogeneous Mixture
Homo means same. The mixtures in which the components have a uniform distribution throughout the mixture are known as homogeneous mixtures.
For example, salt and water is homogeneous mixture as the taste of the water will be the same if you take a sip from any portion of water. This shows that salt is uniformly distributed in the mixture.
Hetero means different. The mixtures in which the components do not have a uniform distribution throughout the mixture which means in which the components are unevenly distributed are said to be heterogeneous mixtures.
Distinguishing Atoms, Elements, Molecules & Compounds
Step 1: Write the symbol or chemical formula of the given substances.
Step 2: Check their composition. If it consists of only one type of atom, then it’s an element.
Step 3: If it consists of two or more atoms of the same type and they are chemically joined, then it’s a molecule.
Step 4: If it consists of two or more atoms from different elements and they are chemically joined, then it’s a compound.
Step 5: Finally, group the substances according to their classification.
What are the different subatomic particles and there usefullness?
Protons
Charge: Positive (+1)
Usefulness: Determines the element’s identity (atomic number) and contributes to the atom’s mass.
Neutrons
Charge: Neutral (0)
Usefulness: Adds mass to the atom and stabilizes the nucleus by reducing repulsion between protons.
Electrons
Charge: Negative (-1)
Usefulness: Involved in chemical bonding and reactions. Determines an atom’s chemical properties and behavior.
What do you find in each periodic table square
Element Name: The name of the element (e.g., Hydrogen).
Element Symbol: A one- or two-letter abbreviation (e.g., H for Hydrogen).
Atomic Number: The number of protons in the atom.
Atomic Mass: The average mass of the element’s isotopes (in atomic mass units).
(Optional) Electron Configuration: Shows the arrangement of electrons.
(Optional) State of Matter: Indicates if the element is solid, liquid, or gas at room temperature.
What are isotopes
Different forms of the same element that have same number of protons but different number of neutrons, still react the same.
What are orbitals
Orbitals are regions around an atom’s nucleus where electrons are most likely to be found.
What is valency?
Valency is the number of electrons an atom can lose, gain, or share to form a chemical bond.
It’s based on the number of electrons in the outermost shell (valence shell).
Example:
Oxygen has a valency of 2 (needs 2 electrons to complete its shell).
Sodium has a valency of 1 (loses 1 electron to become stable).
What are the maximum amount of electrons the subshells can hold and what are the amount of orbitals?
subshells can hold:
s - 2
p - 6
d - 10
f - 14
Amount of orbitals:
s - 1
p - 3
d - 5
f - 7
Order of the spdf thing
1s , 2s , 2p , 3s , 3p , 4s , 3d , 4p , 5s , 4d , 5p , 6s , 4f , 5d , 6p , 7s , 5f , 6d , 7p , 8s.
What is physical and chemical change?
Physical Changes
No new substance is formed.
Only the physical state or appearance changes.
Reversible.
Example: Melting ice, tearing paper.
Chemical Changes
A new substance is formed.
Chemical composition changes.
Usually irreversible.
Example: Burning wood, rusting iron.
Chemical reactions in real life
Cooking food: Heat changes raw ingredients (like baking a cake).
Rusting: Iron reacts with oxygen and moisture to form rust.
Digestion: Food breaks down in your stomach with acids and enzymes.
Burning: Wood or fuel reacts with oxygen to produce heat and smoke.
Photosynthesis: Plants convert carbon dioxide and water into glucose and oxygen using sunlight.
